Adaptive Optics: Mercury Transit: FIRST TIME Test Report: THE MEADE

UNTWINKLING THE STARS p. 30 TO SEE IN A DECADE p. 38 LX600-ACF SYSTEM p. 58

T H E E S S E N T I A L G U I D E TO A S T R O N O M Y

Ancient Origins of
Classical Constellations p. 24

MAY 2016

One
Perfect
Night
GALAXY REVELATIONS
FROM THE DESERT p. 18

Dive Deeper into Shoot the Moon with

Hi-Res Lunar Imaging p. 66 Your Smartphone p. 52
 When I went back to viewing, I wanted the best...
24 f/3.85 Slipstream telescope
and Tele Vue eyepieces.
Tony Hallas

M24 region imaged by Tony Hallas

using a Tele Vue-NP101is refractor.
Tony Hallas,
Renowned Astrophotographer,
Returns to the Eyepiece
(from an unsolicited e-mail to David Nagler)

Hi David and Al,

Although I am still active in imaging, I have decided to go back to viewing and have
taken possession of a new 24 f/3.85 Slipstream telescope from Tom Osypowski. You will
be happy to know that I have acquired a treasure trove of Tele Vue eyepieces to complement
this telescope, specically: 26 and 20mm Nagler Type 5, 17.3, 14, 10, 6, 4.5mm Delos,
Paracorr Type 2, and 24mm Panoptics for binocular viewing. After using a Delos, that
was all she wrote; you have created the perfect eyepiece. The Delos eyepieces are a joy to
use and sharp, sharp, sharp! I wanted to thank you for continuing your quest to make the
best eyepieces for the amateur community. I am very glad that you dont compromise ... in
this world there are many who appreciate this and appreciate what you and Al have done
Tony with his Tele Vue eyepiece collection awaits
for our avocation. Hard to imagine what viewing would be like without your creations. a night of great observing at his dark-sky site.

Best, 25th Annual

Tony Hallas

Tele Vue
./24(%!34
32 Elkay Dr., Chester, New York 10918 (845) 469-4551. televue.com !342/./-9
&/25-
Vi s i o n a r y 3UFFERN.9s!PRIL n
 Eta Carina. ProLine PL16803 & CFW-5-7. Telescope Design: Philipp Keller. Image: Chart32 Team. Image Processing: Wolfgang Promper.

Science or Art? The issue is black and white.

The best astronomical images for science and art are both born from
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2016 Finger Lakes Instrumentation LLC. All rights reserved.

 May 2016 VOL. 131, NO. 5

On the cover: O B S E RV I N G M AY
The spiral M81 is one
of the brightest galax-
41 In This Section
ies visible from Earth,
thanks in part to its
42 Mays Sky at a Glance
young, hot stars.
43 Binocular Highlight
PHOTO: NASA / ESA /
HUBBLE HERITAGE TEAM
By Gary Seronik
(STSCI / AURA)

44 Planetary Almanac
F E AT U R E S 45 Northern Hemispheres Sky
18 Two Cool Galaxies By Fred Schaaf
A clear night gives the author a new-

ETHAN TWEEDIE / WWW.ETHANTWEEDIE.COM

COVER 46 Sun, Moon & Planets
STORY found awe for the incomparable M81
By Fred Schaaf
and M82. By Howard Banich
48 Celestial Calendar
24 Our Surprisingly Ancient By Alan MacRobert
Greek Constellations
52 Exploring the Solar System
Perseus the Wizard, Ursa Major the
By Richard Jakiel
30
Dragon-Wagon many of the classical
Greek constellations were revamped 54 Deep-Sky Wonders
from ages much earlier. By Sue French
By Craig Crossen
Theres more to find online @

30 Untwinkling the Stars

S &T T E S T R E P O R T
58 Meades 10-inch
SkyandTelescope.com
How did the worlds largest telescopes LX600-ACF Telescope
conquer the tempestuous atmosphere? By Dennis di Cicco SKY ON THE GO
By Shannon Hall Find information about all our
ALSO IN THIS ISSUE skygazing apps, from SkyWeek
38 Anomalous Appearances 4 Spectrum to JupiterMoons.
By Peter Tyson SkyandTelescope.com/Apps
How will your observations of the
Mercury transit stack up against the 6 Letters
historical record? By Thomas Dobbins EQUIPMENT GUIDES
8 75, 50 & 25 Years Ago Find advice on choosing the
66 Targeting Luna By Roger W. Sinnott best tools for your backyard
High-resolution close-ups of the Moon
astronomy adventures.
10 News Notes SkyandTelescope.com/
can be a satisfying challenge for modest
equipment/basics
apertures. By Robert Reeves 16 Cosmic Relief
By David Grinspoon
TIPS FOR BEGINNERS
66 62 New Product Showcase Heres everything you need to
jump into the fun.
64 Telescope Workshop SkyandTelescope.com/letsgo
By Gary Seronik

73 Gallery ONLINE STORE

ROBERT REEVES

Shop our online store for books,

84 Focal Point planet globes, and more.
By Greg Bryant ShopatSky.com
SKY & TELESCOPE (ISSN 0037-6604) is published monthly by Sky & Telescope, a division of F+W Media, Inc., 90 Sherman St., Cambridge, MA 02140-3264, USA.
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2 May 2016 sky & telescope

 May 2016 Digital Extra
B ON US E XPLORE O UR
WE B CONTE NT Photo Gallery WE B S ITE!
Two Cool Galaxies: Constellation Basics
M81 and M82 Inspired to learn more about
Test yourself how constellations history and
many details can you mythology? Check out our
spot in M81 and M82? on-demand webinar.

Adaptive Optics: Observe the Moon

Find guides, basic and
Before and After advanced, to help you make
See how adaptive optics
the most of our nearest
changed astronomy in
Image by Amirali Momeni celestial neighbor.
this image gallery.

Gravitational Wave Pocket Sky Atlas Jumbo Edition Astronomy Q&A

Answer your science- and
Get the story on LIGOs A clear and detailed
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& Tel
escope

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22 h 71
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Sky
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HE 694
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12 136
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56
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rica
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59 58 74 68
700 ula IC 5076 (c) 20
V10 0 1
70 51 704 55 Blin
LIB (c) HYD 4 50
Plan king
RA 72 RA
U(c etar
57 26
30 ) 682 y

telescope.
Den Sh2 Z
52 702
7 RU eb -115 2 6
2 W
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1 Pelic Sh2 30 R
IC 506 an Neb Seas O
-112 RT
406
hell
59
706
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PK 80-6 54197 0 Cr 1 686 AX(
c)
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Neb 1311
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Y 2 X 133 y ESO IC 1318
Berk 14
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T 86 87
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k 47 IC 499 Neb cent
699 6
699 2 Sh2 Bas 688 ula 6819
5 -104 el 6 8 19
40 5367
Veil 35 6883 Ced 22

8 by 11
GG Neb 174
ula 27 25
Biur
5786 2 O 394
PK 72-1 32 696 52
Sh2
687
1d
T 0 C YG 5408 -101 15
7.1 NU 39
IC 4444
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31 41 vdB 9
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0 128 4
g IC 4406 17
+20 d 1 5128 8
5882 h469
30 1 257
0 2 IC 495 6
ESO 2 ESO
4-5 (c)
274- 270-
1 33

136 pages
FI IC 4402 21 17
28
1 23 683

OBSERVING
VU ESO 4
2 LPE 221- 19 PK 64+

TOUR THE SKY

CU 26 15 Cen Foo SU
R LA 5460 688 tprin 5139 5.1
24 688 2 t Neb
EL D 29 5 5266 SV ula 9
50 21 h 5927 P H I N Albi = M1-
5946 US 16V744 reo 92
22 Sh2
RCW 17 Sh2 -90
103 Hogg -88 6813
18 b 690 5307 Dum 10
c 5 5286 13 Stoc
Mbbell K

spiral-bound
RCW Neb k1 680
5822 688 ula 0
102 5749 6 M27 683 682
0 3
6067 12
T 5823 64 X 682
Cr 299 0
NO V716 vdB
126
RM 20 h Q
A 5662 v
Cr 292 V
C I RC RV
6087 1 PK 322- INU V381

HIGHLIGHTS
R
2 2.1 Pism S V412 XX

ASTRONOMY PODCASTS
S is 20
V760

stiff cover
5606
ESO h481 Ru 108
137-3 R
4 3 5617 5138
Tr 22
6025 Lyng
vdBH Rigil a2
16 h Cr
60
Sa 172 65a V737 Kent 5316 272
V766
J
Prox
Cent ima Tr 21
auri
15 h 5281
Ced
122
50
14 h m

Sign up for Newsletters and AstroAlerts

THIS WEEKS D OWNLOAD
Sky at a Glance O UR APP S

For Droid

D I GITAL BAC K I S S UE S:
Find us on Facebook ONLINE PH OTO GALLE RY
February, March, and April & Twitter
Giuseppe Petricca captured the full Moon
on Christmas in 2015 in this 30-panel mosaic.
May 2016 sky & telescope
 May 2016 Digital Extra
B ON US E XPLORE O UR
WE B CONTE NT Photo Gallery WE B S ITE!
Two Cool Galaxies: Constellation Basics
M81 and M82 Inspired to learn more about
Test yourself how constellations history and
many details can you mythology? Check out our
spot in M81 and M82? on-demand webinar.

Adaptive Optics: Observe the Moon

Find guides, basic and
Before and After advanced, to help you make
See how adaptive optics the most of our nearest
changed astronomy in
Image by Amirali Momeni celestial neighbor.
this image gallery.

Gravitational Wave Pocket Sky Atlas Jumbo Edition Astronomy Q&A

Answer your science- and
Get the story on LIGOs A clear and detailed
62
Sky
& Tel
escope

hobby-related questions
22 h 71
s Poc
284 ket
Sky
0 Atlas
+50 Jum

atlas, easy to
724
3 21 h bo Edi

first-ever direct detection

7128
RU IC 139 tion
6 C E P vdB 140 61

48
HE 694
B16 B36 US B14 6
4 4 693
1 FZ 8-9 9 20 h
Coc
Neb oon 2
Sky ula CN
720& Tele IC 5146
700
15 h 708 8

or ask your own.

9 scop 6
es PocvdB Le Gen
B16
8 ket145
Sky B362 til 3
Atla 33

consult at the
M39
73
V13 708 46
s Jum 23
39 71 2 bo Edit
LDN
W 970 IC ion

of spacetime ripples.
12 136
54 75 9 14 h
706
+40 2 V11
Nor 704 63 51
56
77 th Ame 7039 8 59 43
5694 47
rica
Neb 60 2
59 58 74 68
700 ula IC 5076 (c) 20
V10 0 1
70 51 704 55 Blin
LIB (c) HYD 4 50
Plan king
RA 72 RA
U(c etar
57 26
30 ) 682 y

telescope.
Den Sh2 Z
52 702
7 RU eb -115 2 6
2 W
70 IC 5070 1 16 CH
1 Pelic Sh2 30 R
IC 506 an Neb Seas O
-112 RT
406
hell
59
706
61 8 ula M83Galaxy
Nor B34
3 Coa thern 6
5824 Piaz lsac
zi's k 6914 6811
LU P C E NFlying Star V36 691
h 5253
US TAU
PK 80-6 54197 0 Cr 1 686 AX(
c)
c c .1 RU S RW 419 6 AF
1 +30 Egg T IC 5161
Neb 1311
ula 2
2 Men M29 Sad IC 4296
V100 kent vdB r
Y 2 X 133 y ESO IC 1318
Berk 14
383-RS(c V97 RR
T 86 87
zP ) Cres 3
k 47 IC 499 Neb cent
699 6
699 2 Sh2 Bas 688 ula 6819
5 -104 el 6 8 19
40 5367
Veil 35 6883 Ced 22

8 by 11
GG Neb 174
ula 27 25
Biur
5786 2 O 394
PK 72-1 32 696 52
Sh2
687
1d
T 0 C YG 5408 -101 15
7.1 NU 39
IC 4444
5483 S V44
31 41 vdB 9
eR 5643 694 5530
0 128 4
g IC 4406 17
+20 d 1 5128 8
5882 h469
30 1 257
0 2 IC 495 6
ESO 2 ESO
4-5 (c)
274- 270-
1 33

136 pages
FI IC 4402 21 17
28
1 23 683

OBSERVING
VU ESO 4
2 LPE 221- 19 PK 64+

TOUR THE SKY

CU 26 15 Cen Foo SU
R LA 5460 688 tprin 5139 5.1
24 688 2 t Neb
EL D 29 5 5266 SV ula 9
50 21 h 5927 P H I N Albi = M1-
5946 US 16V744 reo 92
22 Sh2
RCW 17 Sh2 -90
103 Hogg -88 6813
18 b 690 5307 Dum 10
c 5 5286 13 Stoc
Mbbell K

spiral-bound
RCW Neb k1 680
5822 688 ula 0
102 5749 6 M27 683 682
0 3
6067 12
T 5823 64 X 682
Cr 299 0
NO V716 vdB
126
RM 20 h Q
A 5662 v
Cr 292 V
C I RC RV
6087 1 PK 322- INU V381

HIGHLIGHTS
R
2 2.1 Pism S V412 XX

ASTRONOMY PODCASTS
S is 20
V760

stiff cover
5606
ESO h481 Ru 108
137-3 R
4 3 5617 5138
Tr 22
6025 Lyng
vdBH Rigil a2
16 h Cr
60
Sa 172 65a V737 Kent 5316 272
V766
J
Prox
Cent ima Tr 21
auri
15 h 5281
Ced
122
50
14 h m

Sign up for Newsletters and AstroAlerts

THIS WEEKS D OWNLOAD
Sky at a Glance O UR APP S

For Droid

D I GITAL BAC K I S S UE S:
Find us on Facebook ON LINE PH OTO GALLE RY
February, March, and April & Twitter
Giuseppe Petricca captured the full Moon
on Christmas in 2015 in this 30-panel mosaic.
May 2016 sky & telescope
Peter Tyson
Spectrum
Founded in 1941
by Charles A. Federer, Jr.
and Helen Spence Federer

The Essential Guide

to Astronomy

Goodbye, Hello EDITORIAL

Editor in Chief Peter Tyson
Senior Editors J. Kelly Beatty, Alan M. MacRobert
Equipment Editor Sean Walker
Science Editor Camille M. Carlisle
With this issue we bid a fond farewell to Gary Seronik, whose Web Editor Monica Young
Observing Editor S. N. Johnson-Roehr
articles on observing and telescope making have appeared in S&T for 20
years. Gary recently became editor of SkyNews, the highly regarded Canadian Senior Contributing Editors Robert Naeye, Roger W. Sinnott

astronomy magazine. We wish him the very best in this new endeavor. Contributing Editors Howard Banich, Jim Bell, Trudy Bell, John E. Bortle,
But we cant say goodbye without a quick look back at his substantial contri- Greg Bryant, Thomas A. Dobbins, Alan Dyer, Tom Field, Tony Flanders,
Ted Forte, Sue French, Steve Gottlieb, David Grinspoon, Ken Hewitt-
butions to S&T. A subscriber since age 12, Gary started writing for us in 1996 White, Johnny Horne, Bob King, Emily Lakdawalla, Jerry Lodriguss, Rod
and joined the sta as an associate editor in 1998. Mollise, Donald W. Olson, Joe Rao, Dean Regas, Fred Schaaf, Govert
He quickly took on the amateur telescope-making (ATM) and Schilling, Gary Seronik, William Sheehan, Mike Simmons, Alan Whitman,
Charles A. Wood, Robert Zimmerman
observing columns, and he began helping Dennis di Cicco with
test reports. He launched two new columns, Lunar Notebook Contributing Photographers P. K. Chen, Akira Fujii, Robert Gendler,
and Deep-Sky Notebook, which survive today as Chuck Woods Babak Tafreshi

Explore the Moon and our Going Deep columns, respectively. ART & DESIGN
Gary also worked on books for Sky Publishing. He edited a Design Director Patricia Gillis-Coppola
new edition of Antonn Rkls classic Atlas of the Moon and Chuck Illustration Director Gregg Dinderman
Gary Seronik Illustrator Leah Tiscione
Woods The Modern Moon. He came up with the idea for our
bestselling Pocket Sky Atlas. And he oversaw the publication of ADVERTISING

Binocular Highlights, a compilation of his S&T columns of that name. Advertising Sales Director Peter D. Hardy, Jr.
Digital Ad Services Manager Lester J. Stockman
In 2006, Gary and his wife, Ellen Rooney they met here at S&T
moved back to Garys home province of British Columbia. But he remained F + W, A C O N T E N T + E C O M M E R C E C O M P A N Y

on the S&T sta, continuing to write Binocular Highlights, Telescope Work- CEO Thomas F. X. Beusse
CFO / COO James L. Ogle
shop (TW), and occasional test reports.
VP / Group Publisher Phil Sexton
Beginning with the June issue, two new Contributing Editors will take Senior VP / Operations Phil Graham
over Garys columns. VP Communications Stacie Berger
Mathew Wedel will write Binocular Highlights. By day, Matt is a paleon- Editorial Correspondence (including permissions, partnerships, and
tologist and Associate Professor of Anatomy at Western University of Health content licensing): Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-
Sciences in Pomona, California. By night, as he wrote in 3264, USA. Phone: 617-864-7360. E-mail: editors@SkyandTelescope.com.
Website: SkyandTelescope.com. Unsolicited proposals, manuscripts, photo-
his Binocular Holiday feature (S&T: Dec. 2015, p. 32), he graphs, and electronic images are welcome, but a stamped, self-addressed
is an adventurous stargazer. See his blog at 10minute envelope must be provided to guarantee their return; see our guidelines for
astronomy.wordpress.com. contributors at SkyandTelescope.com.
Jerry Oltion will write a recasting of TW that were call- Advertising Information: Peter D. Hardy, Jr., 617-864-7360, ext. 22133.
ing Astronomers Workbench. A science-ction author of Fax: 617-864-6117. E-mail: peterh@SkyandTelescope.com
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accomplished ATM, whose work Gary has featured several Matt Wedel Customer Service: Magazine customer service and change-of-address
times in TW. See more on Jerry at s.net/people/j.oltion. notices: skyandtelescope@emailcustomerservice.com
Phone toll free U.S. and Canada: 800-253-0245.
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bench will broaden beyond TW to include homemade astro
Visit ShopatSky.com
gear of all sorts, from laser collimators to custom eyepieces. If Your source for the best astronomy resources available
youve got ideas for projects to showcase in this new column, ShopatSky.com customer service: skyprodservice@SkyandTelescope.com
email Jerry at j.oltion@s.net. 888-253-0230.
A nal thanks from all of us to Gary. I was fortunate to Subscription Rates: U.S. and possessions: $42.95 per year (12 issues);
have tremendous teachers, he says. But its the friendships Canada: $49.95 (including GST); all other countries: $61.95, by expedited
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Jerry Oltion ward. Its been a helluva ride. Newsstand and Retail Distribution:
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Sky, SkyWeek, and ESSCO.
Editor in Chief

4 May 2016 sky & telescope

 Letters

General Relativity 101 Since 1977, when I joined the astron-

I very much enjoyed the articles about omy group of the Physics Association
General Relativity (S&T: Dec. 2015, p. 18 in Frankfurt, Germany, I have been
and p. 26). Ive read many papers and privileged to show the wonders of the
articles about GR over the years but have universe to visitors at the groups historic
never seen the basic concept laid out so observatory with an old, 8-inch refract-
clearly. I actually feel that I understand it ing telescope. When the groups size is
slightly better now, and this is no mean not too big, I show o some other nice
feat! I especially liked Alan MacRoberts astronomy objects but the last target,
sidebar in Pedro Ferreiras article (p. if its in view, is always Saturn. When
20) explaining how the curved path of a people look through the telescope and see
tossed ball reduces to a nearly straight this planet for the rst time, the reaction
line in 4D spacetime. Im not sure that Pierre Paquettes brass astrolabes are highly is always overwhelming. You can see this
I completely understand this concept detailed and accurately represent the sky. in their eyes and faces! They dont expect
yet who does? but he denitely got to see such a wonderful natural object. It
me visualizing something in a new way. are small and often minimally useful. In even fascinates our young visitors to
I also like the idea of comparing gravity comparison, my 10-inch model is precise the point that they forget to play with
waves to ripples in a beaten rug! to the minute, after taking into account the their mobile phones!
Tom Sales equation of time and making a correction So, to all astronomers out there: if Sat-
Somerset, New Jersey for longitude (both of which are engraved urn is available to observe, please show it
on the back). to people!
Double-Duty Stars Watson also mentions a craftsman in Alois Juli
There are two stars in Auriga labeled Germany who can make you a stun- Frankfurt am Main, Germany
in the center star charts of the December, ning brass replica. I also found a source
January, and February issues. Will the in France. We three seem to be the only Fear of the Night
real Beta Aurigae please stand up? brass astrolabe makers in the world. Alas! How true Tony Flanderss Night
Dick Jacobson Pierre Paquette Fright (S&T: Jan. 2016, p. 84) rings in
Cottage Grove, Minnesota Pierrefonds, Qubec South Africa. My humble garden has the
misfortune to be invaded by streetlights
Kelly Beatty replies: There are a couple of The Power of Saturn on three sides. Worse still, two neighbors
situations in the sky where a bright star is Dean Regass Focal Point about how on opposite sides of me have blinding
shared by two constellations, and this is one a rst view of Saturn through a small security lights that trespass almost
of them. Elnath, the star labeled in the telescope can be life-changing (S&T: Feb. everywhere. By huddling under a tree and
corner of Auriga closest to Taurus, is in fact 2016, p. 76) is right on the mark. I felt as using my roofs shadow, I can make out
Beta Tauri. The broken purple lines leading if Regas were describing my own experi- 16 to 20 stars. The Milky Way is exiled. So
up to it indicate that its not part of Auriga. ence as a 12-year-old boy, back in the late the weekly meetings of the Cape Centre
Another case occurs in the Great Square of 1970s, when I rst marveled at the car- of the Astronomical Society of Southern
Pegasus. Do you see the two labels? One toon that was Saturn through a friends Africa, the pages of Sky & Telescope, and
of these, Alpheratz, is Alpha Andromedae. 60-mm department-store refractor. NASAs Astronomy Picture of the Day are
That event hooked me in fact, hav- my only windows to the sky.
Modern-Day Astrolabes ing since pursued an education in astro- Keith Gottschalk
Bruce Watsons article about astrolabes physics and employment with NASA, Claremont, South Africa
(S&T: Feb. 2016, p. 24) got my immediate Id say that night certainly changed my
and full attention. It so happens that I life. Regass experience and mine (as
Write to Letters to the Editor, Sky & Telescope,
actually make astrolabes, mainly of brass. well as those of countless others) serve
90 Sherman St., Cambridge, MA 02140-3264,
The unit shown above is what Ive been to highlight the importance of ongoing
or send e-mail to letters@SkyandTelescope.com.
working on lately. educational outreach to todays kids. You Please limit your comments to 250 words.
While Watson is, strictly speaking, cor- never know what a simple look through a Published letters may be edited for clarity & brevity.
rect in noting that you can buy a modern telescope can do. Due to the volume of mail, not all
brass astrolabe on eBay or Amazon for Gary Minarich letters can receive personal responses.
about $200 or a plastic one for $75, these Phoenix, Arizona

6 May 2016 sky & telescope

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 Letters

The Spirit Is Willing 2016, p. 68) with particular interest. I have Star Trails: A Long Story
After many years as a subscriber to S&T, a background in restoring old telescopes, The caption for the photograph of circum-
regretfully I have to cancel. At 91, it is no and when tackling a Brashear 6-inch f/15 polar stars (S&T: Feb. 2016, p. 37) states
longer safe for me to use my observatory. refractor I was amazed and awed by the that the total exposure time was 6 hours.
For more than 22 years I wrote a weekly quality of materials and workmanship But the arcs sure dont look to be quarters
article, Celestial Exploring, for the Wet throughout the instrument. The mechani- of a circle.
Mountain Tribune in Westclie, and I cal complexity and precision machining Ron Adams
relied on S&T for accurate information were especially impressive. In spite of Rochester, New York
on coming sky events. Keep up the good likely being more than 100 years old (and
work, and continue being the top maga- having suered some neglect), this instru- Jeremy Gray replies: My apologies, Ron! The
zine on astronomy. ment required little more than cleaning, original images did indeed span 6 hours,
John Boucek lubricating, and renishing. Except for the but I must have stacked fewer than that to
Pueblo West, Colorado missing nderscope, the only unworkable achieve the desired nal image. Sometimes
part was a badly corroded worm gear, the I process fewer images than I shoot if the
Editors note: Boucek was one of several bracket for which was stamped W&S and ambient sky changes or if the Sun or Moon
local volunteers, led by Jim Bradburn of Wet thus presumably from Warner & Swasey. moves into a signicantly dierent position.
Mountain Valley Dark Skies, who last year Admittedly, these were not mass- This was one of those cases.
succeeded in getting Westclie and Silver market instruments. Still, the words
Cli, Colorado, certied as IDA Dark Sky written by Brashear in the time capsules For the Record
Communities; see wetmtndarkskies.org. letter (every piece of work shall be made Mars will have an apparent diameter of
as perfect as human hands and human 18.4 (not 22) when at opposition on May
More Praise for John Brashear brains can make it) ring true throughout 22, 2016 (S&T: Jan. 2016, p. 54).
I read Al Paslows article regarding the the instrument. Renowned telescope maker John Alfred
demolition of the old Brashear building John F. Rusho Brashear was born in 1840, not 1849 (S&T:
and nding its time capsule (S&T: Jan. Fulton, New York Jan. 2016, p. 70).

75, 50 & 25 Years Ago Roger W. Sinnott

May 1941 May 1966 case the visitor detected
Wartime Optics [Given] Cloud Satellites In 1961, the Polish astrono- a patch of light.
our countrys defense mer [Kazimierz] Kordylewski reported his Despite such seeming
program . . . Eastman discovery of two large, faint patches of light conrmations, astrono-
Kodak is searching for moving around the earth in the same path as mers have never fully
men to make optical the moon, one of them 60 degrees ahead of it, embraced Kordylewskis
instruments on a the other 60 degrees behind. . . . A particle at cloud satellites.
production basis, and either of these two points would continue in
has communicated with stable orbital motion, forming an equilateral May 1991
several amateur groups. triangle with the earth and moon. Buckyballs in Space
. . . Undoubtedly, there are amateur telescope Kordylewski described the cloud satellites Does interstellar space abound with car-
makers who could easily qualify for such work, as several degrees in diameter . . . resembling bon-60 molecules shaped like soccer balls?
but the problem is to nd those who wish to do the gegenschein, but fainter. [Their crystals, recently made in a lab,]
it, and who are not already so employed. . . . J. Wesley Simpson, of Lockheed Missiles represent a new, third kind of solid carbon (in
To go to Springeld, Vt., the cradle of ama- and Space Co., now reports that he and R. G. addition to graphite and diamond). . . . Soccer
teur telescope-making, would do little good, Miller have made repeated observations of the balls and the geodesic domes of R. Buckmin-
for in that booming town . . . all amateurs are cloud satellites from Locksley Observatory, in ster Fuller have the same geometry, leading
busily engaged in the machine tool trades so the Santa Cruz Mountains of California. . . . scientists to refer to C60 as buckminsterfuller-
vital to defense. On several dates ene or bucky balls.. . .
As for amateur observers constellation, when one of the cloud Surprisingly, tests on the spectrum of C60
variable star, meteor, and aurora students satellites was favorably . . . have so far failed to match astronomical
would they not form an excellent nucleus for a placed, visitors to Lock- observations. But the chemists havent given
civilian night patrol? If for no other reason than sley Observatory were up yet. There is still a possibility that some of
their being used to long hours of observing, asked to scan the appro- the unidentied interstellar bands might arise
amateurs ought to make good sky watchers. priate area of the sky, from ionized C60 [reports Donald R. Human,
Editorials like this one, penned by Editor without being told what University of Arizona].
Charles A. Federer Jr., reected growing concerns to expect. According to That linkage nally succeeded last year (S&T:
during the early days of World War II. Mr. Simpson, in every Nov. 2015, p. 14).

8 May 2016 sky & telescope

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 Learn more about the discovery and watch
News Notes videos explaining gravitational waves at
http://is.gd/gravitationalwaves.

PHYSICS I Gravitational Waves Detected,

Discovery Heralds New Era of Astronomy
On February 11th LIGO scientists announced the direct Based on the gravitational waves frequency, team
detection of gravitational waves, a discovery that will members estimate that the colliding black holes had
smash wide open a new door on the cosmos. the masses of about 36 and 29 Suns, respectively. LIGO
Gravitational waves are ripples in the fabric of space- watched all three predicted phases of the collision: the
time, predicted by Einsteins general theory of relativity black holes death spiral, the ensuing merger, and the
(S&T: Dec. 2015, p. 26). Theyre created by accelerating ringing of the merged object as it settled into its new
masses, much as paddles sweeping through water spur form. The newly created black hole contains about 62
vibrations in a pond. Previously, astronomers only had solar masses; the gravitational waves carried away three
indirect evidence of their existence. But at 9:50:45 Uni- solar masses worth of energy, just as predicted.
versal Time on September 14, 2015, LIGOs two L-shaped With only two detectors, LIGO cant pinpoint the
labs one near Hanford, Washington, and the other in sources exact location it could come from anywhere
Livingston, Louisiana caught the gravitational-wave within about 600 square degrees of sky near the Large
signature of two colliding black holes. Magellanic Cloud in the Southern Hemisphere sky. The
LIGO detected the signal shortly after both its facilities source has a redshift between 0.05 and 0.12, meaning
turned back on following ve years of intensive upgrades. the waves traveled between 700 million and 1.5 billion
The instruments shoot infrared lasers through 4-kilo- years before reaching us.
meter-long arms of near-perfect vacuum. The laser light The team claims a 5.1-sigma detection, meaning the
reects o ultrapure, superpolished, and seismically odds of the signal occurring by chance are about one in
isolated quartz mirrors. The passing gravitational waves 3.5 million. The result appears in Physical Review Letters.
slightly altered the path lengths in the arms of both The direct detection of gravitational waves opens up
detectors, by about 1/1000 the width of a proton. That slight an entirely new spectrum that doesnt involve any form
change created an interference pattern in the laser light, of light. As LIGO member Eric Katsavounidis (MIT) puts
which LIGO scientists detected as an event. Theyve it, This is the end of the silent-movie era in astronomy.
dubbed the event GW150914. Gravitational waves are incredibly dicult to detect,
for three main reasons: (1) gravity is the weakest of the
Vibrations as Gravitational Waves Passed four known forces of nature, (2) the strength of the
waves falls o sharply as they traverse space, and (3)
Inspiral Merger Ring- matter barely feels their presence. The gravitational
down
waves from a distant galaxy that are detectable to LIGO
are squeezing and stretching the Milky Way Galaxy by
the width of your thumb, says science team member
Chad Hanna (Penn State University).
1.0 LIGO began its rst advanced observing run last
detectors length (10 21)
Fractional change in

fall, but improvements continue and future runs will

0.5 have at least twice the sensitivity and enable LIGO to
0 survey 10 times the volume of space. Theorists predict
Advanced LIGO should catch an additional ve binary
0.5 black hole mergers in its next observing run. They also
expect roughly 40 binary neutron star mergers every
1.0 year it runs, and an unknown number of black hole-
neutron star mergers and supernovae.
0.30 0.35 0.40 0.45
Although the detected merger went entirely according
Time (seconds)
to predictions, scientists hope to eventually see discrep-
This reconstructed signal from LIGO shows the last few orbits ancies that could provide vital clues to new physics,
of the black hole duos dance of death, the merger itself, and the potentially reconciling contradictions between relativity
ringdown as the newly formed black hole settled down. and quantum theory.
S&T: GREGG DINDERMAN / SOURCE: LIGO SCIENTIFIC COLLABORATION AND VIRGO COLLABORATION /
PHYSICAL REVIEW LETTERS 2016 (DOI10.1103/PHYSREVLETT.116.061102) ROBERT NAEYE

10 May 2016 sky & telescope

 SOLAR SYSTEM I Is There a Ninth Planet?
these copycat orbits couldnt simply be a
holdover from the solar systems forma-
tion over time, subtle perturbations
2013 RF98 from the giant planets would cause them
to slowly drift apart.
2004 VN112
Instead, something must be actively
2007 TG422 imposing this orbital order. Batygin
2012 VP 113
and Brown invoke a massive hypotheti-
cal body, which theyve dubbed Planet
Nine, with at least 10 times Earths mass
90377 Sedna (two to four times its diameter). It would
Planet Nine occupy a highly elongated orbit that
averages about 700 a.u. from the Sun and
never comes nearer than roughly 300 a.u.
Such an object would naturally explain
2010 GB 174
not only the clustered perihelia but also
CALTECH / ROBERT HURT

the dynamically puzzling orbits of Sedna

and its kin.
So where is this putative planet? Actu-
ally, a wide range of orbits is possible,
with periods ranging from 10,000 to
The six most distant known objects in the solar system have orbits (shown in purple) that remain 20,000 years. The Batygin-Brown predic-
beyond Neptune and which align in one direction. A hypothesized massive planet (orange orbit) tion requires a highly elongated orbit,
could be maintaining this perplexing alignment. which means that most of the time the
object lingers near aphelion. So it should
Does a massive, extremely distant planet Batygin and Brown have taken this be no brighter than roughly magnitude
orbit the Sun? A new analysis of distant idea to the next level. Their analysis 22 beyond the range of most ground-
solar system orbits argues that it should shows that the solar systems six most and space-based surveys to date.
exist. Writing in Februarys Astronomical distant objects not only have clustered Even if the proposed Planet Nine is
Journal, Konstantin Batygin and Michael arguments of perihelion (as its known never seen directly, the circumstantial
Brown (Caltech) describe how Kuiper Belt technically) but also follow elliptical case for its existence might be strength-
objects that average at least 150 astro- orbits oriented the same way in space, ened once observers discover more very
nomical units from the Sun and never angled below the ecliptic plane by about distant Kuiper Belt objects and assess
come closer than about 50 a.u. share an 30. Theres only a 0.007% chance of this their orbital distribution.
interesting dynamical property. Their having occurred by chance. Moreover, J. KELLY BEATTY
perihelia all cluster near the ecliptic plane
and theyre all moving south to north
when they pass through perihelion.
This orbital clustering started to IN BRIEF projects website, palereddot.org, or by fol-
lowing the Twitter hashtag #PaleRedDot.
draw attention after the discovery of the
Hunting for Planets Around Proxima Meanwhile, Proxima Centauris passage in
object 2012 VP113 a few years ago. In
Centauri. Astronomers are ramping up front of a background star in February gave
announcing that nd, Chadwick Trujillo
their search for exoplanets orbiting the the Hubble Space Telescope an opportu-
(Gemini Observatory) and Scott Sheppard
nearest star to our solar system. The Pale nity to look for microlensing events. These
(Carnegie Institution for Science) noted
Red Dot initiative, led by the European are small spikes in the background stars
the perihelic similarity of 2012 VP113,
90377 Sedna, and 10 other bodies (S&T: Southern Observatory, is a campaign to brightness that a planet orbiting the red
July 2014, p. 14). Moreover, these objects examine the red dwarf star Proxima Cen- dwarf could produce as it passes in front of
occupy a dynamical no mans land that tauri for exoplanets using the radial veloc- the star, magnifying the starlight as a lens
dees easy explanation for how they got ity method, which teases out the signal of would. Read more about the endeavors at
there. Trujillo and Sheppard concluded a planet tugging on its host star. You can http://is.gd/proxcen2016.
that a massive planet, even farther out, follow the Pale Red Dot campaign on the DAVID DICKINSON
might be responsible.

Sk yandTelescope.com May 2016 11

 News Notes
T get astronomy news as it breaks,
To
vvisit skypub.com/newsblog.
MARS I Gullies Triggered by Dry Ice?
Researchers are circling back to the fresh, cut into older terrain yet largely In the January Nature Geoscience,
idea that carbon dioxide ice might be free of erosion. researchers Cedric Pilorget (IAS/
responsible for some or all of the gullies These gullies are dierent from (and CNRS, France) and Franois Forget
on Mars. In 2000, images from NASAs much larger than) the occasional, sea- (LMD/CNRS, France) suggest a forma-
Mars Global Surveyor revealed hundreds sonal trickles of salt-infused water seen tion scenario that involves no water at
of these features, trailing down crater elsewhere on the surface, which create all. Instead, they invoke frozen carbon
rims all over the Red Planet (S&T: Sept. the so-called recurrent slope lineae (S&T: dioxide (dry ice), which coats all of the
2000, p. 56). They looked geologically Jan. 2016, p. 14). Martian polar terrain each winter and
Initial speculations focused on the even extends to poleward-facing slopes
idea that water was seeping out onto the at lower latitudes. This explanation
surface and cutting little channels as it builds on a dry-ice-powered process rst
owed downslope. Yet many gullies occur proered by University of Melbourne
in frigid polar regions or on heavily shad- researcher Nick Ho man in 2002.
owed slopes facing toward the poles. Careful modeling by Pilorget and
The gully debate reignited last year Forget shows that the annual frosting of
when images from NASAs Mars Recon- dry ice can become transparent enough to
NASA / JPL / UNIV. OF ARIZONA

naissance Orbiter showed that many allow sunlight to pass through to ground
gullies are evolving right now cutting level. Ice in contact with the Sun-warmed
more deeply into their surroundings soil sublimates into gas but remains
and creating aprons of debris farther trapped under the overlying slab. Gas
downslope, sometimes more than once. pressure builds and eventually lifts and
Images taken in 2010 (left) and again in 2013 Modern-day Mars is far too cold and dry cracks the slab, causing the trapped gas
by NASAs Mars Reconnaissance Orbiter show to harbor the substantial near-surface (along with entrained dust) to cascade
that an existing gully recently formed a new reservoirs of liquid water that could downslope, forming or enlarging a gully.
branch (indicated by the arrow). explain this behavior. J. KELLY BEATTY

MILKY WAY I Galactic Hit-and-Run IN BRIEF

A few hundred million years ago, a vatory, Poland) has arisen over whether Limit on Black Hole Gluttony. Once
small galaxy had a fender-bender with the stars are true Cepheids. Due to the a black hole reaches about 50 billion
the Milky Way. Even as it ed the crime Polish teams work, three of the four stars times the mass of the Sun, the disk of gas
scene, it sent ripples coursing through were rejected. that acted as its dinner buet begins to
the Milky Ways disk. Now with the Chakrabartis new study, announced crumble apart. Andrew King (University of
help of a trio of brightly pulsating stars, January 7th at the winter American Astro- Leicester, UK) presents this conclusion in
Sukanya Chakrabarti (Rochester Institute nomical Society meeting in Kissimmee, the February 11th Monthly Notices Letters
of Technology) and colleagues say they Florida, adds two new stars to the list of of the Royal Astronomical Society. A more
have found the fugitive dwarf galaxy. potential members of the sought galaxy. massive black hole will have a larger disk
Last year, Chakrabarti and her team But its still unclear whether these three
feeding it than a smaller hole will. But King
found four stars located toward the Norma candidates are Cepheids; they could be
calculates that, above the limit, the disks
constellation the exact spot where, back binaries or stars with dark spots only
gas will collapse into clumps, forming
in 2009, she and Leo Blitz (University of mimicking a Cepheids pulsation.
stars. To continue growing, the black hole
California, Berkeley) had predicted the Whether or not the trio prove to be
would need to swallow clumps (or stars)
runaway galaxy is hiding. The astrono- Cepheids, Chakrabarti does think they
mers hoped the four stars were Cepheids, are a good starting point. Follow-up whole. Since the glow from accretion disks
standard candles that regularly expand observations of the shift in the stars is what enables observers to see these
and contract at a rate directly related to spectral lines reveal velocities that all dark objects, more massive black holes
their intrinsic brightness. If so, the team clock in at roughly 156 km/s (349,000 might be truly invisible: astronomers would
would be able to use the stars variations mph) an order of magnitude larger need to turn to more indirect means, such
to conrm their distances. than typical velocities of stars in the disk as gravitational lensing, to nd the biggest
But since then, a debate between of our galaxy. So they clearly dont belong behemoths. Gas disks have revealed black
Chakrabartis team and that of Pawel to the Milky Way. holes up to around 10 billion solar masses.
Pietrukowicz (Warsaw University Obser- SHANNON HALL ALLEN ZEYHER

12 May 2016 sky & telescope

 R A T
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 News Notes

STELLAR I Spotting Twins of Eta Carinae BLACK HOLES I The

Disappearing Quasar
Astronomers tracking a distant quasar
over a span of 13 years reported January
8th at the American Astronomical Society
meeting in Kissimmee, Florida, that all
signs of the quasar have disappeared.
The quasar, known as SDSS
J1011+5442, was rst detected in 2002.
A follow-up spectrum collected the next
year showed all the signs of hot gas
NASA / ESA / HUBBLE HERITAGE TEAM / R. KHAN (GSFC AND ORAU)

feeding a typical, ferociously gobbling

supermassive black hole sitting at the
center of a galaxy.
The quasars brightness declined
steadily over the next decade, far more
Eta Twin-4 Eta Twin-5 systematically than usually happens with
The galaxy M83 hosts two potential
twins of Eta Carinae. These candi- such objects. When Jessie Runnoe (Penn
dates (insets, not resolved) seem to State University) and colleagues observed
have warm, dusty shrouds much like the quasar again as part of the Time
the one that envelopes Eta Car. Domain Spectroscopic Survey in 2015,
2 arcseconds they took a visible-light spectrum of the
beasts disk of gas. They found nothing
almost all signs of the quasar had van-
Astronomers looking for clones of the 26 million light-years away: M51, M83, ished. Instead, they saw only a relatively
huge, unstable star Eta () Carinae have M101, and NGC 6943. Together, these ordinary galaxy. The team published
potentially found ve in other galaxies. galaxies produced 20 of the Type II (core- its results in the January 11th Monthly
Eta Car is one of the most massive collapsing, big-star-killing) supernovae Notices of the Royal Astronomical Society.
stars in the Milky Way, estimated to seen in the last century. And here is This isnt the rst case of a disappear-
have 120 Suns worth of material. It where the astronomers found ve objects ing quasar; astronomers now know of
pumps out more than 5 million times that look just like Eta Car. several changing look active galaxies (as
the energy than the Sun does, but it and Look just like is used loosely, Khan theyre collectively known).
its companion star hide inside a double- explained January 6th during a press The best explanation for J1011+5442s
dumbbell of dust and gas called the conference at the American Astronomi- disappearance is a diet, in which the black
Homunculus Nebula. cal Societys biannual meeting. The ve hole cut its feeding rate by a factor of 10.
Astronomers havent seen any stars objects are too distant to be resolved. The accretion disk should still surround
quite like Eta Car, but they want to. Such But the light coming from these sources it, though. The outermost part of the disk,
massive, evolved stars created many of behaves just like that from Eta Car. The which is responsible for the light, would
our galaxys heavy elements, and these sources are relatively faint in near- normally take 800 years to gradually
megastars might also be the culprits infrared and visible light, as seen by empty out and fade, Runnoe says. Instead,
behind what are called superluminous the Hubble Space Telescope, but theyre she suggests that rather than clear its
supernovae, stellar explosions that are bright at mid-infrared wavelengths, as plate completely in the few short years
strangely bright compared with their kin. seen with the Spitzer Space Telescope. theyve been observing, the quasar swal-
Observers havent had much luck Moreover, their brightness attens out lowed the nearest, hottest gas from the
looking for Eta Carinaes twins, though in this mid-infrared range, in a manner inner accretion disk. This could happen
theyve turned up several candidates. thats a spot-on match for star-envelop- quickly, in a month or two. The hot, inner
Rubab Khan (NASA Goddard) and his ing dust thats been warmed to between gas would have emitted ultraviolet light as
team are narrowing the search by looking 400 and 600 kelvin. Thus, the team it swirled toward the black hole, irradiat-
in other galaxies for dust-enshrouded members are pretty sure theyre seeing ing the outer disk to make it glow. So
stars whose visible and infrared light light from massive, evolved stars, as when the ultraviolet beacon near the black
closely matches Eta Cars. they also explain in the December 20th hole went dark, the outer disk would have
The team looked at four bright, star- Astrophysical Journal Letters. lost its visible-light shine as well.
forming spiral galaxies that lie 15 to CAMILLE M. CARLISLE MONICA YOUNG

14 May 2016 sky & telescope






  25th Annual
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Cosmic Relief
David Grinspoon

Our Year In Space

ISS astronauts are reviving our passion for space travel in novel ways.

Im writing this near the end of Astronaut

Scott Kelly and Cosmonaut Mikhail Kornienkos Year
in Space. Since March 2015, these men have orbited our
planet in the International Space Station. Its easy to take
the ISS for granted. Ill admit at times Ive grumbled
about its share of the NASA budget compared with that
of my own pet planetary probes. But the Year in Space
has rekindled the idealistic and romantic excitement,
fueled by the Apollo missions and science ction, which
as a kid had me imagining we would soon be widely
inhabiting the solar system.
Kelly and Kornienko have been using themselves
as experimental subjects, gathering valuable data on
human responses and adaptations to long-duration
spaceight that will be key for missions to Mars or else-
where. Life has evolved for 4 billion years in close concert
with the Earth, and today we humans are perfectly Scott Kelly aboard the International Space Station, July 2015

NASA
attuned to its surface environment, in ways that become
obvious when we leave it. transformational potential of the space experience.
Space changes us physically, with the lack of gravity Scott Kelly has used social media artfully to commu-
especially taking its toll. Space also aects people psy- nicate both daily details and moments of insight. With
chologically and spiritually. Those who have seen Earth his #EarthArt series he shares stunning images of our
from above report a sense of profound communion with planetary home presented with casual but sharp descrip-
all of humanity and with the biosphere, and a feeling tions, curating in real time an awe-inspiring art project
that our global conicts would ease if more people could for the growing number of Earths inhabitants who have
gain that perspective. Unfortunately, only a small num- an internet connection. He often wishes us good morn-
ber of individuals have been in orbit and experienced ing or good night from space with a stirring view of a
this overview eect. crescent Earth, an iridescent thin band of blue shining
Yet something has changed in the way we are now against the great darkness.
experiencing space. The Year in Space is part of a Yes, we humans are well adapted to Earths land sur-
delightful trend of astronauts taking advantage of social faces but deeper in our history was a time when life was
media and other tools to share their experiences in new conned to the oceans. The move to the harsh environs
and more direct ways. The connection with people on of the land was dicult but ultimately worth it. Perhaps
the ground has become deeper and livelier. the halting beginning of our extraterrestrial stage is a
Commander Chris Hadeld made Earths rst astro- moment of similar evolutionary potential. Our planet
naut music video: David Bowies Space Oddity, actually as it really is indivisible, beautiful, and precious is
performed while oating in a tin can far above the world. revealed to us through the space perspective. The more
It was an inspired choice. Bowie, who was 10 years old people who see it, the better equipped well be to meet
during Sputnik, poetically explored space travel as a the global challenges of the coming century.
metaphor for risk and transcendence.
Art helps us connect with and process the universe David Grinspoon is an astrobiologist, author, and senior
that science reveals. And now, by showing their artistic scientist at the Planetary Science Institute. Follow him on
sides, astronauts are sharing more broadly the inspiring, Twitter at @DrFunkySpoon.

16 May 2016 sky & telescope

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 Sweet View

Two Cool Galaxies

The Incomparable M81 and M82

Sometimes, during a great night, the atmosphere around 40F. Dawn was an hour away, the air per-
will get out of the way for a while. The early morn- fectly still. Conditions were superb.
ing hours of October 13, 2015, produced one of these Orion was nearing the meridian when it occurred
extraordinary moments while I was observing from to me to turn around and have a look at M81 and
Steens Mountain in southeastern Oregon. M82, which had risen in the northeast and were now
The sky had been exceptionally transparent all level with Polaris.
Howard night, and by 4:30 a.m. an intense zodiacal light was Id been working on detailed drawings of both
Banich well up in the east. My observing buddy, Rod Shea, galaxies since 2011, and while pushing my 28-inch
had already hit the sack. telescope to their position, I remember thinking the
The seeing had been a mess all night but was view might be pretty good. Little did I know M82 was
quickly sharpening as the temperature stabilized about to blow me away.

18 May 2016 sky & telescope

 been a major factor in shaping it into the highly dis-
turbed object we see today.
Even at low power in a small scope a good deal of
chaotic mottling can be seen along the central half of its
edge-on prole. In progressively larger scopes this mot-
tling resolves into a fascinating jumble of dark lanes and
bright splotches.
This untidy appearance is M82s dening visual
characteristic and is the reason for its alternative desig-
nation as Arp 337. It really does look peculiar and so
distinctly appealing.

Superwind
Although theres a 30 million-solar-mass supermassive
black hole (SMBH) in the center of M82, its the ongo-
ing starburst activity and subsequent supernovae in and
around the core that create its famous bi-polar super-
wind. The superwind is the outow extending north and
south from the center of M82 and forming the lacy red
wings seen in the image to the left.
The southern superwind is the easiest to see in a
telescope and extends farthest from the core, but the
northern superwind is often impossible to detect with
any certainty. Theyre both brightest near the ends of the
central dark lane.
The lamentary nature of the superwind creates the
random-looking dark areas that crisscross the central
prole of the galaxy. However, some of these dark lanes
are interstellar dust, raw material for future star forma-
tion. Its fascinating that this pre-stellar dust looks so
similar to the post-stellar outow.
The superwind wings are an obvious part of M82s
photographic appearance, but visually they rest on the
far side of subtle. That makes objectivity during an
observation especially important because our brains
are wired to expect them after seeing so many detailed
photos of M82.
JOHANNES SCHEDLER

Super Star Clusters

On both sides of the central dark lane are massive
star-forming regions in the core, shining through the
outows and dust. These areas are Super Star Clusters
(SSCs). These SSCs formed 4 to 6 million years ago in
CLOSE COMPANIONS Can you think of one without the the latest surge of star formation. They are con ned to
other? M81 (left) and M82 (right) have been gravitationally the central 1,600 light-years of the galaxy and dene the
interacting for approximately 500 million years, along with starburst region in optical wavelengths.
galaxy NGC 3077 (not shown). The most obvious of these relatively young clusters
are labeled A, C, D, and E in the annotated drawing on
M82 is dierent the next page (these designations follow from OConnell
A starburst galaxy, M82 is the closest, brightest, and and Manganos paper on the central regions of M82 in
most active of its kind. Its most recent encounter with Astrophysical Journal, 1978). Together, they make up the
M81, about 200 million years ago, sparked its intense arrow-shaped area just west of the central dark lane.
star formation. The ongoing starburst not only makes I rst saw them on a night of superbly steady seeing
M82 the brightest external galaxy in infrared light, its at Chuck and Judy Dethlo s property in the Oregon

Sk yandTelescope.com May 2016 19

 Sweet View

M82 Coast Range Mountains in 2011. They looked best at

812. At this magnication the SSCs sparkled with tiny,
star-like knots in the 28-inch scope a fantastic sight!

Shapes
The superwind and dust overlay of the central area cre-
ates some intriguing features, the most prominent of
which is the hourglass-shaped dark lane cutting M82 in
half. This is the most reliable dark feature for observa-
tion along M82s length. All the other dark and bright
features are smaller, and can seem tossed together willy-
nilly at low power.
The eastern core Region B can be particularly
uncertain. A major starburst area about 100 million
years ago, its now settled down. The tiny bright spot
labeled B2-1 can only be seen at high magnication with
steady seeing.
More generally, the eastern half of the galaxy appears
fairly straight, while subtle curves embellish the western
Region B half. The brightest arc begins with a slight northeast
twist then gracefully turns west while fading into the
blackness of intergalactic space.

Southern Superwind So what blew me away at Steens Mountain?

After centering M82 in my low-power eyepiece I
bumped up the magnication to 408. I was immedi-
Region A ately stunned to see easily see the highly complex
Region C Source B2-1 superwind and dust lanes silhouetted against the central
Region E Northern Superwind portion of the galaxy in exquisite detail. Wow!!
Region D
It was simply beyond expectation to see this extrava-
gant level of resolution. I was astonished and completely
surprised by this intricately woven veil of black lace it
was a fantastically delicate and awesome sight. This gave
the central area of M82 an appearance reminiscent of
a naked-eye view of the summer Milky Way, which is a
remarkable comparison to make with a galaxy 11.8 mil-
lion light-years away.
There are faint details in many deep-sky objects that
force me to check my preconceptions to make sure what
Im seeing is real, usually because Im putting a great
deal of eort into seeing them. This was the opposite of
that, and remains one of the most memorable sights Ive
seen through any telescope.

M81 is beautiful
N The view of M81 from Steens Mountain was also the
most gorgeously detailed Ive ever seen it just wasnt
SUPERWIND & SSCS as staggering a sight as M82.
I used observations gathered over a M81 looked magnicent, though, with a fully realized
four-year period, using magnications view of its grand design spiral features, sprinkled with a
ALL SKETCHES BY THE AUTHOR

ranging from 155 to 812, to make this

handful of details I hadnt been able to see before.
drawing of M82. An IO spiral galaxy
seen edge-on, M82 is about 37,000
A classic SA(s)ab spiral, M81 is the epitome of a beau-
light-years in diameter. At magnitude tifully symmetrical and serene-looking two-arm galaxy,
8.4, its 1.5 magnitudes fainter than and a perfect contrast to the apparent chaos of M82.
M81. North is to the right. Unfortunately, many of M81s features are dicult to see

20 May 2016 sky & telescope

M81

Holmberg IX

Spiral Disk Southern Spiral Arm

Region D
Region A

Region B

Region C

AGN

Region E

Region F

Northern Spiral Arm Region G

Spiral Disk

SPIRAL SPECTACULAR My drawing of M81 is based on four

years of observations using magnications from 155 to 408.
Each of the labeled regions is an assortment of many objects,
with details of each posted at http://is.gd/coolgalaxies. Note the
dwarf irregular galaxy Holmberg IX at upper center as a faint,
diuse area it was formed 200 million years ago during a
close encounter between M81 and M82. Its nearly as faint as
the spiral disk area of M81. North is to the right.

Sk yandTelescope.com May 2016 21

 Sweet View

well even though its 1.5 magnitudes brighter than M82.

M82 Larger and more spread out, its visibility depends highly
on sky conditions and the experience of the observer.
Its startling how much can be seen through a great
high altitude sky, yet even when conditions arent top
notch, M81 is a remarkable place to explore.

The Core
Any telescope will show the bright, oval core, which
is the easiest part of M81 to see. Along with its even
brighter nucleus, theyre the rst things youll notice.
Sometimes theyre the only things visible if the sky is
too bright to reveal the spiral arms, or if your scope isnt
large enough to show them.
Either way, as you get accustomed to the view you
may begin to see more.
The major axis of the core is slightly oset from that
of the spiral arms an interesting feature to look for
because it doesnt show up in photographs.
The core builds in brightness toward the center and
is suddenly punctuated by the bright nucleus. This
is M81s active galactic nucleus (AGN). At its center, a
massive amount of energy is coming from the compact
region around its 70 million-solar-mass SMBH. Thats
DARK AND DUSTY Inverted close-up showing the intricate pretty big for a galaxy approximately 90,000 light-years
dark lanes of the superwind and interstellar dust this is a across with nearly the same mass as the Milky Way. (For
close representation of what I saw at Steens Mountain. The
comparison, the Milky Ways SMBH contains about 4
magnication was 408, producing a 2-mm exit pupil in my
million solar masses.)
28-inch scope.
The outer and less bright part of the core is slightly
fainter on the northern side, throwing o its symmetry.
M81 Its also attended by several foreground stars, the three
brightest of which form a nearly straight line on the
cores southern side. You may also spot several fainter
stars superimposed on the core, but they need steady
seeing and decent magnication. For instance, look just
a few arcseconds south of the AGN for a star thats nearly
overwhelmed by the cores brilliance.
Along the western border of the AGN is a thin, curved
dark lane that shows up nicely in most photos. Its not
easy to see telescopically, though the rst time I saw it
was at Steens Mountain. It was dimly visible with direct
vision at 408 but averted vision really made it pop.

Spiral Arms
Close encounters with M82 probably gravitationally
enhanced M81s spiral arms, but theyre still under-
stated, low-contrast features. They also compete with the
bright core, making them a dicult target in less than
optimal observing conditions.
In my experience, theyre best seen with medium
magnications. I used 120 with my old 12.5-inch Dob,
A CLOSER LOOK This inverted close-up illustrates how M81 and 253 with my 28-inch. In my 8-inch scope Ive seen
looked at Steens Mountain through my 28-inch scope. Both a suggestion of the arms at 69.
this and my M82 drawing above show the averted vision view On the best nights my 28-inch shows each arm nearly
built up over 4 years of sketching. wrapping completely around the core, but theyre still

22 May 2016 sky & telescope

subtle. The southern arm is slightly easier to see, espe- the southern spiral arm. It might look slightly fuzzy on
cially along its most highly curved outer edge. The ends the best nights. The northern arm yielded three regions.
of each arm taper and blend into a larger oval glow that Along with starlike E, the small condensations of F and
denes the complete spiral disk. G were found in the barely undulating fog of this some-
This glow is the dimmest part of M81s structure, what featureless area.
extending the galaxys shape and lling the area By the way, each region is a conglomeration of many
between the arms. Its much fainter than the arms and objects H II and star clusters, X-ray, UV, infrared,
is best detected by looking for a subtle decrease in sky and SNR sources making their barely seen glow even
brightness beyond the disk. more exotic.
M81s apparent size nearly doubles when this soft Although these details give M81 added depth and
glow is detected. The arms look longer and the symmet- character, the galaxy is more than the sum of its parts.
rical beauty of the galaxy becomes more apparent. This Its the combination of its classic grand design shape and
can be a hard-won sight though, and another one where synergetic relationship with M82 that ultimately makes
objectivity is needed. it and them so captivating.

H II Regions and Star Clouds Together

Ive often been able to detect subtle mottling along the These two galaxies have profoundly reshaped each other.
brightest and highest contrast portion of the southern Observing them together is not only one of astronomys
arm through my 28-inch while using averted vision. great sights, it helps convey the reality of their connection.
This corresponds to some of M81s H II regions and star A telescopic view large enough to see the apparently
clouds. However, until this past October I hadnt seen serene M81 and the obviously agitated M82 in context
any of the brighter patches individually. to each other, and to intergalactic space, is a big part of
It took Steens Mountains transparent, high-altitude what makes observing them so extraordinary.
skies, and 408, to pull them out. Surprisingly, these The scene looks tranquil at rst. Majestically tilted
small, faint, and fuzzy patches were visible even when toward each other, the galaxies vast and breathtaking
the seeing was poor. dynamism becomes apparent with even a little familiar-
I noted the most distinct group of H II regions A ity of their long history.
and B on my sketch. Along with C, the faintest region, Were seeing just the latest frame of a 500 million-
theyre equally spaced starting just south of a super- year-long movie. Now 300,000 light-years apart, M81
imposed foreground star along the most dened edge and M82 are still roiling from their latest encounter,
of the southern arm. Region D is the easiest to see, only seemingly suspended in their grand and inexorable
appearing as a faint star-like object on the east side of gravitational ballet.

IN THE BEGINNING This was the wide-angle view through Howard Banich lives in Portland, a long but scenic drive
my homemade 8-inch f/4 Newtonian from my suburban front from Steens Mountain in southeastern Oregon. He can be
yard in 1975. The streak in the upper left corner was a tele- reached at howard.banich@nike.com.
scopic meteor.

Sk yandTelescope.com May 2016 23

 Earlier History

Our Surprisingly Ancient

Greek Constellations

BALAGE BALOGH

Perseus the Wizard, Ursa Major the Dragon-Wagon many of the

classical Greek constellations were revamped from ages much earlier.

The standard versions of our familiar constellations, Modern scholarship has traced many of our Greek
with their Greco-Roman mythologies that most skygaz- constellations to prototypes in cultures of Mesopotamia
ers learn early in their starry pursuits, (modern Iraq) that were about as distant in time from
CR AIG CR OSSEN arent half the story. The ancient Greeks the ancient Greeks as we are from them. Some constel-
gave us our 48 classical constellations, but many of lations date back at least to the origin of writing, which
these were already extremely old, inherited and adapted seems to have happened in Sumeria, just north of the
from very dierent societies long extinct. Persian Gulf, around 3200 BC. This suggests that these

SUMERIAN ORIGINS The ancient city of Uruk, in the marshy waterways of Sumeria north of Eridu, grew to become the worlds
largest city by the late 4th millennium BC, with an estimated 50,000 residents. Invented here were the wheeled wagon and its
constellation counterpart, as well as the plow, the cylinder seal, the rst true writing, and monumental architecture such as the
White Temple of Anu, the sky god. In this illustration, the temples design and that of the surrounding neighborhoods are based on
excavations and mapping of what are now crumbling bricks in the desert.

24 May 2016 sky & telescope

 constellations may be older still: literally prehistoric. text calls it the Axle of the Sky, and another states that
In an earlier issue, I described the Sumero-Baby- it stands the entire year. Were the skywatchers of the
lonian prototypes of the Greek water constellations time really so unobservant? Or does putting the celestial
that ll our southern sky in autumn (S&T: March 2015, pole in the middle of the scene correctly describe a larger
p. 36). Now lets look to the northern side of the sky. tableau? Indeed it does, as we shall see.
While the ultimate origins of the water constellations Babylonian and Assyrian astronomical texts of the
are lost in the prehistory of far-southern Mesopotamia last two millennia BC associate the northern heavens
(in particular the city ruined of Eridu), the birth dates with the air- and weather-god Enlil, an older Sumerian
of some of our northern constellations can be estimated deity. This suggests a special relationship between
more accurately. Enlil and the prominent celestial Wagon. And indeed,
One of them, for instance, had to follow the invention cylinder-seal designs from as far back as the mid-3rd
of the wheel. millennium BC show Enlil standing in his wagon. The
wagon has a long, arched draft-pole in front, correspond-
Wagon of the North ing to the Dippers handle. The drawing below is from a
The most conspicuous star pattern in the northern heav- cylinder seal of the Akkadian Period, around 2300 BC.
ens is the Big Dipper, which marks the hindquarters It shows Enlil, whip in hand, in his Wagon. Its being
and surrealistically long tail of the classical Great Bear. pulled by a winged lion-grin, its head down and its
Originally, however, the Big Dipper itself seems to have gaping jaws spewing ame or venom. Enlils consort
been the entire Bear, because in both the Iliad and the Ninlil, the goddess of the wind with thunderbolts in
Odyssey (approximately 8th century BC), Homer says the each hand, stands on the creatures back.
Bear is also called the Wagon (in Greek, Hamaxa) a Enlils Lion-Gri n carried into Greek astronomy
shape thats suggested by just the Dipper itself. as the constellation Draco the Dragon, which stands
The Greek celestial Wagon is a direct borrowing from in front of the Dipper/Wagon. Today the Wagon seems
ancient Mesopotamia, where it was called Margidda, the to precede the Dragon around the celestial pole as the
Long [i.e., four-wheeled] Wagon. But the word mar- sky turns, but during the 3rd millennium BC the north
gidda is Sumerian, implying that the Dipper stars took celestial pole was near Alpha Draconis (Thuban), so the
this identity before 2000 BC, when Sumerian ceased to Wagon and most of the Dragon pivoted closely around
be a living language. This is conrmed by its appearance the pole opposite each other. The arrangement is seen
in Sumerian star-name lists written around 2000 BC and on the next page, with the dots connected as they appear
by its mention in an old Sumerian myth called (by mod- on Sky & Telescopes star charts. The complete scene
ern scholars) Enki and the World Order, which seems
to have been composed around 2500 BC. THE DIPPER STARTS HERE Enlil, the god of the northern constel-
The Mesopotamians declared that the Wagon was cir- lations, rides his celestial Wagon (Margidda, our Big Dipper), pulled by
cumpolar, but in a way that at rst seems unrealistically a celestial grin, probably Draco the Dragon. This is a drawing of the
exaggerated. A late (1st millennium BC) astrological impression from a cylinder seal of the Akkadian Period around 2300 BC.
W. H. WARD, THE SEAL CYLINDERS OF WESTERN ASIA (CARNEGIE INSTITUTE, 1910)

Sk yandTelescope.com May 2016 25

 Earlier History

Sumerian, Ban) formed by the star-pattern of Kappa-

Epsilon-Sigma-Delta-Tau Canis Majoris and Xi-Rho
WA GO N Puppis, with Sirius as the copper-headed arrow (Kaksisa)
shot from it along the Eta-Delta-Alpha Canis line. (Cop-
Pole star per was the most advanced material in military technol-
ogy at that time, as emphasized by Siriuss brightness.)
Thuban _ In the northern celestial hemisphere the Sumerians
DRA GO N placed a celestial Plow, Apin, which apparently consisted
of Gamma Andromedae plus our classical Triangulum,
SKY & TELESCOPE

with the plows narrow tip at Alpha Trianguli. The deep-

tilling Sumerian plow with a seeder funnel (depicted
below) was invented, like the four-wheeled wagon,
AROUND THE FORMER POLE Enlils wagon and its draft- around 3200 BC. In fact, there was a burst of creativity
beast appear in their modern versions on Sky & Telescopes sky at Uruk in the late 4th millennium BC, when the wagon,
charts. They revolved as a pair around the north celestial pole, the plow, the cylinder seal, monumental architecture,
which was near Thuban at the time. the potters wheel, and true writing were all invented.

therefore stood all year on the axis of the sky, as the The Saga of the Kneeler
later Babylonian texts reported. Concerning the star pattern we know as Hercules, the
Theres a popular notion that most or all of the clas- Greek astronomical poet Aratos wrote in his Phaenom-
sical constellations come from religious mythology, but ena of 270 BC, That sign no man knows how to read
thats not correct. Sumerias humble Wagon constella- clearly, nor on what task he is bent, but men simply call
tion is a case in point. The four-wheeled wagon seems to him On His Knees [Greek: Engonasin]. The constel-
have been invented at the southern Mesopotamian city lation was not known as Hercules until at least the
of Uruk around 3200 BC at least the earliest known late 2nd century AD, when the cult of Hercules grew
picture of one is on a cylinder-seal impression found in increasingly popular in the Roman Empire. All the early
a stratum in the ruins of Uruk dating to about that time. Greek and Roman writers on astronomy Aratos, Hip-
Given the resemblance of the Big Dipper to the prole of parchus, Geminos, Vitruvius, Manilius refer to this
the Sumerian wagon with its arched draft-pole, its safe star-pattern simply as The Kneeler.
to say that the constellation Margidda was invented after No Sumerian, Babylonian, or Assyrian astronomi-
the wagon itself: in other words, after about 3200 BC. Its cal or astrological text mentions a celestial Kneeler. In
still sometimes called the Wain or Wagon in England. fact, MUL.APIN, the great Assyrian astronomical work
A half-dozen archaic Sumerian constellations were compiled before 1000 BC, calls the stars of our Hercules
named for what were then newfangled inventions. Thus Urku, the Dog. Worse, images of kneelers are so fre-
we nd in the Sumerian heavens a celestial Bow (in quent in ancient Near Eastern art that it would appear
hopeless to identify a celestial Kneeler among them.
But during the Old Babylonian period of the early
H. FRANKFORT, CYLINDER SEALS FROM THE DIYALA REGION

2nd millennium BC, a cylinder-seal design featuring a

particular kneeler happened to be especially popular. It
shows him being attacked by a rampant lion or a ram-
pant lion-grin, sometimes both. The Kneeler is almost
always accompanied by a seated goat likewise attacked by
a lion-grin and/or a lion, as shown on page 28. Several
(UNIV. OF CHICAGO, 1955)

decades ago the assyriologists Edith Porada and Briggs

Buchanan recognized this seal design as astronomical,
pointing out that the Goat and the Lion-Grin were
neighboring Sumerian constellations, occupying the
stars of Lyra and Cygnus-Cepheus, respectively.
TAMING OF BEASTS Hydra, with a roaring lion, pulls a
What they overlooked was that our Hercules is right
Sumerian plow equipped with a narrow funnel-seeder as two
there next to them, just west of the Goat, our Lyra.
deities guide it. One of them goads Hydra with a scorpion. The
pointed plowshare end of the Sumerian constellation Apin, the
Moreover, in the sky the Kneeler is upside-down with
Plow, later became the Greeks narrow Triangulum. The serpent respect to the Lion-Grin in a vanquished position,
creature here, with its long, scaled body, upraised head, and as is shown in the cylinder-seal design. So I think we do
horned crown of godhood, is identical to later Mesopotamian indeed nd the celestial Kneeler in Mesopotamia, occu-
portrayals of Hydra the constellation. pying the correct area of sky, 1,500 years before Aratos.

26 May 2016 sky & telescope

 HENRI FRANKFORT, CYLINDER SEALS FROM THE DIYALA
REGION (UNIVERSITY OF CHICAGO, 1955)

NINURTA AND THE HYDRA A drawing of a cylinder-seal design from the mid-3rd millennium BC, found on a number of
pieces of clay excavated at Tell Asmar northeast of Baghdad. The bottom row shows a kneeling Ninurta ghting a seven-headed
snake. Two heads have been cut o at the neck; the gure holds at least one of them.

But this does not put a name on him. However, about Nor was the association of dogs with Bau and Ninurta
a millennium earlier in Mesopotamia, another Kneeler arbitrary: these were war deities, and on Sumerian cyl-
gured prominently in cylinder-seal designs, and this inder-seal designs and steles, dogs are shown following
one can be identied. He is ghting an assortment of war-wagons into battle and feeding upon the battle-dead.
mythological monsters, including serpents, caducei, How did the Heroic Kneeler of the early 3rd millen-
spread-eagles, and most importantly seven-headed nium become the Vanquished Kneeler of the early 2nd
snakes or dragons. In all cases the Kneeler is the Van- millennium? Perhaps the change was another conse-
quisher, not the Vanquished. quence of the severe cultural dislocations in Mesopota-
And he is named. According to the Sumerian myth mia after the collapse of the Sumerian Ur III Dynasty
Lugal-e of the late 3rd millennium BC, the Vanquisher around 2000 BC. For the next two centuries Mesopota-
of the Seven-Headed Serpent was the war-god Ninurta. mia was in social, political, and economic chaos. It was
Here then we seem to have the origin of both the Greek during this time that Sumerian ceased to be a living
celestial Kneeler and the Greek myth of Hercules tack- language. Much of the high culture of the Sumerian 3rd
ling the multi-headed Hydra. millennium was lost, or misunderstood by the invad-
This role of the celestial Kneeler seems supported ing nomadic tribes. Thus the star-gure of the Kneeler
by the fact that his upright foot is always shown on the remained in the sky, but perhaps his identication and
head of Draco. Indeed, in the early 3rd millennium BC mythological associations were forgotten.
when the north celestial pole was near Alpha Draconis, Similarly, as told in my previous article, the Water-
if you looked high in the north from Mesopotamian Pourer (our Aquarius) remained in the sky but on
latitudes when the Kneelers head (Alpha Herculis, Ras-
algethi) was near the zenith, you would have seen Draco
HENRI FRANKFORT, CYLINDER SEALS

curved out beneath his feet. The classical Hercules is

portrayed with his club raised as if to pound his victim.
Vanquisher indeed.
(MACMILLAN, 1939)

This also helps explain why MUL.APIN called this

star-pattern Urku, the Dog. Ninurkas consort was the
goddess Bau, and her sacred animal was the dog. Vega,
far and away the brightest star in this part of the sky, was
Baus star. Apparently her icon, the dog, was transferred HEROIC KNEELER A kneeling gure (left) seizes two
late in Mesopotamian history to the sky-image of her caduceus-snakes by their necks in this drawing from a cylinder
husband one constellation over. seal dating to around 2700 BC.

Sk yandTelescope.com May 2016 27

 Earlier History

VANQUISHED
KNEELER After
the fall of Sumeria,
the Kneeler was not
so heroic. A winged
grin chomps on a
powerless gure, and
a lion seems to have
bitten a weapon from
his upraised hand,
in this cylinder-seal
impression from the
Old Babylonian period
around 1700 BC. On
the left a similar crea-
ture attacks a goat,
whose constellation
was positioned next
to the Kneeler in the
Mesopotamian sky.
W. H. WARD, THE SEAL CYLINDERS
OF WESTERN ASIA (CARNEGIE
INSTITUTE, 1910)

later cylinder seals was often shown as one of the gods Cepheus, the King; Cassiopeia, the Queen; Pegasus, the
themselves rather than as a mere human priest of Enki, Winged Horse; and Cetus, the Sea Monster. The story
which he had been originally. is such an excellent example of ancient Greek myth-
making an art at which that people excelled that
Perseus the Sumerian its hard to believe that most of its constellations have
The best-known Greek sky legend is the tale of Perseus Sumero-Babylonian roots.
and Andromeda. The Greeks elevated all its major This is immediately clear from the objects Perseus
players to the heavens: Perseus with his scimitar and himself carries: the Head of the Medusa and the Scimi-
Medusas head; Andromeda, the chained maiden; tar with which he cut it o. The Greek Medusa head a

PROTO-MEDUSA for a proto-Perseus. Masks

of Humbaba (or Huwawa) the Terrible, a demon-
monster whose very look brought death, were tools
of the trade for Mesopotamian exorcists and magi-
cians. This one was used during animal-entrail divi-
nation around 2000 BC or a bit later. Humbaba stars
in the epic of Gilgamesh and Enkidu, dated to about
2100 BC. His face was made of serpentine lines rep-
resenting intestines; they squirmed and coiled like
the later Medusas living hair-snakes. Enkidu cut o
Humbabas horrible head and carried it in a leather
sack, as did Perseus with the head of Medusa.
Humbaba and the early Greek representations of
Medusa displayed similar grimaced mouths. The
Babylonians placed their demon-head and another
BRITISH MUSEUM

wizards tool, the curved sta, into the northern sky

with Shugi, the Old Man, likely the pre-Perseus.

28 May 2016 sky & telescope

 (Enif), the Nose of Pegasus according to the Greeks.
However, this could not date to the Sumerian 3rd mil-
lennium BC because horses were not used in Mesopo-
tamia, and virtually never shown in Mesopotamian art,
before 2000 BC. Indeed, the image of a celestial winged
horse only appears in Mesopotamia in the Middle Assyr-
ian Period around 1200 BC. Its presence in the sky by
that time no doubt gave rise to our Pegasus.
Historians have known for two centuries that some
constellations we inherited from the Greeks have
Mesopotamian roots. Whats surprising, however, is the
extent of the Greek debt to the Sumerians, Babylonians,
and Assyrians for constellation gures we would have
assumed were Greek innovations, such as the Winged
Horse, the Medusas Head, and the Hydra. Even more
surprising, perhaps, is that entire Greek myths were
based on Mesopotamian originals, such as the battle of
Hercules with the many-headed Hydra snake.
But the Greek genius was in how they used the
images and themes they inherited: they turned it all into
poetry. Literally so, in the case of Aratos and his owery
enumeration of the classical 48. And that surely has
helped preserve them ever since.

Craig Crossen is a freelance writer, editor, and traveler who

frequent motif in Greek art is practically identical to calls Minnesota home base. He co-authored Sky Vistas
earlier Mesopotamian demons heads made of terracotta (2004) and is completing books on the history of all the clas-
that were used in magic, exorcism, and divination. An sical constellations and on the history of archaeology in Iraq.
example is pictured at the bottom of the facing page.
And in Mesopotamia, Perseus Scimitar (Harpe in
Greek) was named Gam, though assyriologists disagree C lu b Rasalgethi
about which stars represented it. In Sumerian the word He a d
gam referred not only to a curved weapon, but also to the
curved sta used by magicians and exorcists. Moreover,
in this same region of the sky the Sumerians placed
a constellation called Shugi, the Old Man. A better
NI NURTA
translation, given the presence here of a celestial magi- T HE GOAT
cians Sta and Demons Head, might be Exorcist or KNE E L E R
Diviner. Thus it would seem that the athletic super-
hero Perseus, carrying a scimitar and the severed head Vega
Ba os
of the dreaded Medusa, descended from a Sumerian Foot S ta r
Kn e e
celestial wizard holding two tools of his trade.
The celestial Andromeda and her parents Cepheus He a d
and Cassiopeia seem to be purely Greek innovations. In
Mesopotamia the Cepheus stars were the hindquarters
of a large celestial Lion-Grin that included Cygnus.
Cassiopeia was the Stag. Andromeda is made of stars Thuban
from three Mesopotamian constellations: the Plow, the
Northern Fish of the Mesopotamian predecessor of D R AGON
SKY & TELESCOPE

Pisces, and the northeast-corner star of the Sumerians

Irrigated Field, which was our Great Square of Pegasus.
But the Greek Pegasus was not a totally new sky-
gure: MUL.APIN lists a Horse Star between the HEROIC ONCE AGAIN From the Roman era to ours, Her-
celestial Eagle (Aquila) and the Irrigated Field. Only cules wields a club as he kneels with his foot over the head of
one bright star matches this placement: Epsilon Pegasi Draco. This is their portrayal on Sky & Telescopes star charts.

Sk yandTelescope.com May 2016 29

 Adaptive Optics

Untwinkling the
How did the worlds largest
telescopes conquer the
tempestuous atmosphere?
SHANNON HALL
Stars

ETHAN TWEEDIE / WWW.ETHANTWEEDIE.COM

The rst few days of an observing run can be enchant- The team had mounted GPI on the immense 8.1-meter
ing: the night sky so dark that familiar constellations are mirror of the Gemini South telescope, and the instru-
hard to nd, the landscape typically barren and far from ment would nally begin its planet search during this
city lights, and the array of mirrors and instruments observing run. But it still had to go through an extended
nally catching beams of light from the distant universe. testing sequence, and Macintosh was nding the work
But on one such evening in November 2013, high in tedious he was anxious to get on sky.
the remote Chilean Andes, Bruce Macintosh was bored.
Macintosh (Stanford University) led the team that ARTIFICIAL STARS Twin laser beams from the Keck tele-
built the Gemini Planet Imager (GPI), the rst in its scopes atop Mauna Kea, Hawaii, create articial guide stars to
class of next-generation adaptive optics instruments. aid adaptive optics observations of our galaxys center.

30 May 2016 sky & telescope

 So on the fourth night, after the team of engineers Deep (and Classied) Roots
responsible for the tests headed to bed, Macintosh took Many early scientists, even Isaac Newton, wrestled with
matters into his own hands. That was the night where the problem of atmospheric distortion, but the real
we said, yknow, lets just point it at a damn planet advances didnt begin until the 1970s. Thats when the
and see what it looks like. The team slewed the tele- Pentagon was working on something seemingly unre-
scope toward Beta Pictoris, a star 63 light-years lated to astronomy: it needed a way to focus
from Earth with a hot, young giant planet a laser beam on a distant target, which
that orbits its star at almost twice the meant protecting the beam from choppy
distance that Jupiter orbits the Sun. wind. At the same time, DARPA, an
Then they waited but not for long. agency within the Department of
Within 60 seconds a lump had mate- Defense, wanted to identify satellites
rialized on the screen before them. launched by the Soviet Union.

N A DA
The same detection prior to GPI Even at a good location, atmo-

C CA
would have taken an hour to image spheric turbulence smears out details

NR
and days to process. Could the new smaller than 1 arcsecond across. Thats

S/
OI
instrument capture an exoplanet in good enough to see the cylinder-shaped

AR
M
AN
TI
only a minute? The astronomers lling HR
IS Hubble, which is similar in size to most
B YC
the room remained skeptical. They franti- PRO CE
S SIN
G
spy satellites, but not good enough to make
cally grabbed their laptops and searched for any out details. The military needed a way to do better.
papers that might show an image of the planet Beta If scientists could accurately measure how the
Pictoris b. They then scrutinized the screens, holding atmosphere is moving, they could send that information
their laptops sideways to better match the images ori- along to a exible secondary (or tertiary) mirror. In prin-
entation on the observatorys computer screen. Sure ciple, this deformable mirror would exactly cancel distor-
enough, the images aligned. Before their eyes was a tions introduced by the atmosphere into the primary
newborn gas giant, seen more clearly than ever before. mirrors image, sculpting the rays of light (from a satel-
Spotting the exoplanet right o the bat was an lite or any other target) back to near-perfect alignment.
incredible feat, says GPI chief scientist James Graham One of the rst AO demonstrations was installed in
(University of California, Berkeley). It doesnt require 1980 on DARPAs 1.6-meter telescope in Maui. It used
any detailed analysis. It doesnt require crunching the 168 piezoelectric actuators, which expand or contract
numbers. Its just completely evident in the raw data that in response to applied voltage, to very slightly bend a
an exoplanet is there. deformable mirror. Today, AO systems might contain
But the basis of GPIs success was decades in the many thousands of these mirror movers, thanks to
making. Even 2,700 meters (8,900 feet) above sea level, improvements in their manufacturing, positioning,
Gemini South still sits beneath an ocean of air. So the
telescope uses adaptive optics (AO) to correct for the
turbulent atmosphere. In GPI, more than 4,000 actua-
tors spaced just 400 microns apart deform the instru-
ments secondary mirror to exactly match and cancel out
atmospheric distortion. Without AO, light from planets,
stars, and galaxies would dance and distort, like pebbles
seen beneath a owing stream. The colossal observatory
wouldnt see any sharper than a backyard scope. But
with AO, images steady themselves, allowing astrono-
mers to pick out ne details.
The technology that makes this feat possible was
born in the 1970s in classied government meetings. A
GEMINI OBSERVATORY

few select Air Force scientists and astronomers worked

together to design early versions of laser guide-star
systems before the project was declassied in 1991. After
several decades of innovation, AO is still improving with
each new generation. Today, ground-based telescopes BETA PIC Top: One of the rst images the Gemini Planet Imager took was of
such as Gemini South can exceed the clarity of the the disk around Beta Pictoris, a star known to host a planet. With just a min-
Hubble Space Telescope. And the next generation of AO- ute-long exposure, the newborn gas giant appeared on screens in the control
equipped mega-telescopes will push the boundaries of room. Above: The Gemini Planet Imagers rst-light images brought elation to
sight even further. the team in the control room at the Gemini South telescope in Chile.

Sk yandTelescope.com May 2016 31

 Adaptive Optics

and mounting.
Subject to But even with the best deformable mirrors, compen-
be studied
sating for the atmosphere is no easy task. The simplest
method calls for a star in the eld of view, which would
look like a small point if its light could travel undis-
turbed to the telescope. The atmosphere introduces any
er Articial star
Sodium lay extra blur. So keeping a telescopic eye on the star gives a
measure of atmospheric turbulence.
But theres a catch: in order to measure the rapidly
changing atmosphere, astronomers need to catch a lot
of photons quickly, so the star has to be pretty bright.
No star fainter than 10th magnitude would do, and even
if stars were evenly distributed, only 15 stars this bright
would be found in each square-degree patch of the sky.
This limitation wouldnt be so bad if it werent for a
second one: only a very tiny area of the sky around the
star up to about 30 arcseconds wide for images at
near-infrared wavelengths will have similar atmo-
spheric turbulence. The two conditions leave only 1% of
Atmospheric the sky available for AO observations. There had to be
turbulence
another way.
So in the late spring of 1982, the military called on
the Jasons a group of scientists who meet once a year
to give technical advice on issues of national security
to help solve the problem. In that classied think tank,
scientists came up with a potential solution: shine a laser
upward along a telescopes axis and you can create a
bright articial star wherever you like.
Image distorted With that in mind, Air Force scientist Robert Fugate
by atmosphere
and colleagues created a Rayleigh laser guide-star system
at the Kirtland Air Force Base in Albuquerque, New
Mexico. Molecules in the lower atmosphere such as
Sodium oxygen, nitrogen, and aerosols reect the laser beam,
laser creating a green-colored spot of light in the sky. Fugate
and his colleagues pointed their system toward a pair of
Telescope
stars in Ursa Major, capturing an image 25 times clearer
Corrected
Deformable image Camera than previous work. The researchers were well on their
mirror way to conquering the age-old problem of turbulence.

Declassifying AO
But at the time fewer than 100 people in the world knew
S&T: GREGG DINDERMAN

Wave about it. Many Jasons spent years lobbying the military
sensor to take the wraps o, but it wasnt until the Soviet Union
fell apart (and spy satellites became less of a threat) that
the military considered declassifying the information.
Scientists around the world had started to catch up
HOW ADAPTIVE OPTICS WORKS As starlight shines anyway two French astronomers published a paper
through Earths atmosphere, turbulent air distorts its wave- describing the technique in 1985. Finally, in 1991 Fugate
front. A blurry image results. In a laser guide-star AO system, was allowed to describe the research at a meeting of the
a sodium laser shoots up to the mesosphere, scattering
American Astronomical Society in Seattle, Washington.
among the sodium atoms there to create what appears to be
Prior to that meeting I had never talked about this
a bright yellow star. Computer algorithms measure this arti-
cial stars wavefront, which is similarly jangled by the time with more than 10 people in the room, Fugate recalls
it reaches the ground. The computer then deforms a exible more than 20 years later. But by the start of his talk,
mirror to return both wavefronts to their undisturbed forms. the room had lled up with nearly 400 people, some of
whom were standing three to ve deep all around the

32 May 2016 sky & telescope

 from the ground.
By the early 1990s a few sodium lasers had been
built, but none powerful enough to do the job. It was
over lunch one day that Max and a colleague realized the
necessary laser was sitting beneath their feet. Livermore
Laboratory had an enormous underground laser that was
normally used to separate isotopes but could be tuned to
sodium wavelengths. So one night Max set up a mirror
to bounce the horizontal laser beam up into the sky. She
UNDER AN OCEAN OF AIR Despite its incredible see-
then pointed a small telescope at the guide star and mea-
GEMINI OBSERVATORY

ing conditions, the Gemini South telescope pictured here sured the atmospheres disturbances. It was proof that
still requires adaptive optics to overcome the tempestuous she could improve upon Fugates existing system, and
atmosphere above it. by 1996 Max and colleagues had deployed a prototype
at Lick Observatorys 3-meter telescope. But even then
most observatories failed to embrace the technology it
walls. I was as nervous as I could be, Fugate says. was too expensive.
But he did not disappoint. Utter silence followed his In 1999 a $20 million grant from the National Science
announcement, then noisy chatter lled the room. Foundation kick-started the Center for Adaptive Optics.
Although it was clear that adaptive optics was the tool Astronomers from the University of California and
astronomers needed, the current system was far from per- Livermore continue to work together to improve upon
fect. Take Fugates laser system. Because it used Rayleigh existing technology and further develop the techniques
scattering in the lower atmosphere, it could only shine up necessary to use it. Now, even though laser-assisted AO
to about 20 kilometers above Earths surface. Still more air systems still have to be custom-built for every observa-
above this layer remained unmeasured. tory, most large telescopes have joined the game.
So another Jason involved with the project, Claire
Max (then at Lawrence Livermore National Laboratory), Outshining Hubble
worked on a better solution: if a laser is tuned to a spe- In optics the motto is generally, the bigger, the better.
cic wavelength (589 nanometers), it will excite a layer of A larger primary mirror captures more photons and
neutral sodium atoms oating about 90 kilometers above enables astronomers to see fainter and farther objects. It
Earths surface. Initially deposited by meteors passing also determines the level of detail the telescope can pick
through the atmosphere, these sodium atoms will uo- out, as long as atmosphere isnt an issue. The Hubbles
resce in response to the lasers light an eect visible 2.4-meter mirror can resolve objects 0.1 arcsecond apart

GREEN VS. YELLOW

Green-tinted Rayleigh
lasers, such as the
ones being installed
at the Large Binocular
Telescope (left), are
commercially avail-
able and therefore
cheaper. They reect
JULIAN ZIEGLEDER / MAX PLANCK INSTITUTE FOR EXTRATERRESTRIAL PHYSICS

o a lower layer of
the atmosphere and
account for distortion
nearer the ground.
Lasers tuned to 589
nanometers, such as
the one employed by
the Gemini South tele-
scope (right), reect
o the higher-altitude
sodium layer about 90
GEMINI OBSERVATORY

kilometers above the

ground.

Sk yandTelescope.com May 2016 33

 Adaptive Optics

Find a full gallery of before-and-after images at

http://is.gd/adaptiveoptics.

at 1 micron, but only because it ies about 350 miles

above Earths surface. With the advent of adaptive optics,
one of Kecks 10-meter telescopes (among the largest
HEIDI B. HAMMEL AND IMKE DE PATER / WMKO

observatories in the world) can resolve details as ne as

0.04 arcsecond producing images more than twice as
crisp as Hubbles.
In 1999, the Keck Observatory placed its rst natural
BEFORE AND AFTER Without adaptive optics, a near-infrared image
guide-star system on Keck II and a year later on Keck
of Uranus appears blurry (left). When the same image is taken with AO
I. With better deformable mirrors and even the ability
technology turned on (right), the faint and fuzzy ring resolves into sev-
eral distinct rings, and small storms within the atmosphere are revealed.
to separate light into its constituent wavelengths, this
system was radically improved in comparison to earlier
AO counterparts.
Such razor-sharp vision enabled astronomers to peer
TUNING IN TO into the crowded environment at the center of the Milky
SGR A* Astrono- Adaptive Way Galaxy. Before getting access to Kecks adaptive
mers used com- Optics OFF optics, Andrea Ghez (University of California, Los Ange-
plex techniques les) and her team had used a camera that took exposures
to reveal action in every few milliseconds to create stacked images of this
our galaxys center region. But from 1995 to the present day, Ghezs team has
before adaptive been able to watch stars orbiting the Milky Ways center at
optics (top). closer distances than ever before. These previously hidden
With the advent stars whip as close as 45 astronomical units to the center,
of AO (bottom),
at speeds up to 12,000 kilometers per second (roughly
astronomers
4% the speed of light). Yet the center appears empty. The
have pinpointed
source of gravity thats inging the stars in their speedy
and tracked the
orbits cant be anything but a supermassive black hole.
UCLA GALACTIC CENTER GROUP / W.M. KECK OBSERVATORY LASER TEAM (2)

minute motions
Adaptive
Although Ghez herself is modest about this achieve-
of individual stars
Optics ON ment, other astronomers think her research is without a
as they careen
around Sgr A*, our
doubt the best example of AOs successes. I dont have
galaxys supermas- words to express how stunning that is, says GPIs Macin-
sive black hole. tosh. Its both just visually stunning to watch as a human,
The larger square and scientically its really, really important.
elds are 6 on a Then in 2003, Keck II upgraded its AO system to
side, insets span use a sodium laser sent from Maxs team at Livermore
1, and all images (Keck I followed suit a few years later). Peter Wizino-
were taken at wich, who leads AO development at Keck, has spent
wavelengths near the past two decades improving the technology. He has
2.2 microns. commissioned new lasers, better deformable mirrors,
and faster code to work seamlessly between the two. As
such, Kecks AO system is the most productive one in
astrophysics: to date, its responsible for roughly 70% of
T. NAKAJIMA / S. DURRANCE; S.
KULKARNI / D. GOLIMOWSKI /
NASA; M. CHUN / NICI TEAM

refereed-science papers that use adaptive optics.

Orbits seem to be the theme of Kecks rst AO
results. A couple years after Ghezs work, a team includ-
ing Macintosh used the Keck II and Gemini North
telescopes to directly image three pinpricks of infrared
ADAPTIVE OPTICS REVOLUTION The AO-enabled Palomar Observa-
light around HR 8799, a 6th-magnitude star in the
tory discovered the rst brown dwarf, Gliese 229B, tucked within the glare of constellation Pegasus. In theory such direct images of
its companion star (left). Hubble followed up a year later (center) to help pin exoplanets could reveal their composition, climate, and
down its orbit. After a decade, an image captured by the Near-Infrared Coro- even possibilities for life. Though this rst image wasnt
nagraph and AO system on the Gemini North telescope (right, in a slightly yet up to that task, the discovery laid the groundwork for
larger eld of view) shows how far the technology has come. direct-imaging systems (S&T: Oct. 2015, p. 16).

34 May 2016 sky & telescope

 TO INFINITY A laser
Star guide star shines down
from a layer in Earths
Articial atmosphere a lot closer
guide star than real stars, which might
as well be innitely far
away. As a result, articial
starlight shines down in a
cone (left), rather than in
Deformable the cylindrical shape of real
secondary mirror starlight (right). So atmo-
spheric turbulence wont
aect light from an articial
star in the exact same way
as light from a real star.
Primary mirror Future AO systems will use
S&T: GREGG DINDERMAN

multiple laser beams to cor-

Beam splitter Beam splitter rect for turbulence within a
larger area of the sky.
Computer Camera Computer Camera

The Next Generation: Megascopes day and night roughly every 45 minutes. This change
But the most expensive and ambitious spree of tele- warms and cools the spacecraft and changes its focus.
scopes and their accompanying adaptive optics has Although the beloved space telescope doesnt have AO,
only just begun. Giant observatories currently under its successor, the James Webb Space Telescope, will
development include the Thirty Meter Telescope on launch with a built-in AO system.
Mauna Kea, the European Extremely Large Telescope in
Chile, and the Giant Magellan Telescope also in Chile. Stumbling Blocks
When it comes to building billion-dollar behemoths, Its safe to say that laser adaptive optics has revolution-
adaptive optics is a must. Increasing the size of these ized astronomy, but it does present several observing
telescopes primary mirrors would mean nothing if the challenges. Contrary to popular belief, articial laser
atmosphere were to limit their resolution to 1 arcsecond. guide stars dont allow astronomers to see any celestial
But cancel out the atmosphere, and a 30-meter telescope object on any clear night of the year. Astronomers still
could spot objects as small as 0.008 arcsecond across. need a second (real) guide star albeit very faint to
Megascopes will need improvements in laser technol- make a few basic corrections. With this restriction, laser
ogy if theyre to implement AO. While the light from a guide-star AO currently covers 70% of the sky, largely in
star innitely far away will fall through the atmosphere the galactic plane where there are more stars.
in a cylinder its rays of light perfectly parallel a Also, sodium beacons dont work perfectly every day
sodium laser guide stars light falls through a tall cone of the year. The blanket of sodium in the upper atmo-
that peaks at the sodium layer. Since its rays arent per- sphere thickens every time Earth tumbles into a stream
fectly parallel, a single sodium guide star cant perfectly of meteors. So the sodium layer will be densest Sep-
mimic a star. The larger the telescope, the more that tember through December, after the brightest meteor
dierence begins to matter. showers of the year (namely the Perseids, Geminids, and
The 30-meter telescopes are going to require not a Orionids) deliver their bits of sodium. Unfortunately,
single laser but a grid of laser beacons, each of them with this is when the weather is often poorer. During the
their own cone, to try to reconstruct the atmospheric tur- optimum observing conditions of summer, astronomers
bulence in three dimensions, Macintosh says. Demon- may struggle to produce a bright-enough beacon of light.
stration systems have been deployed at the Gemini South Finally, theres one more minor and sometimes
telescope and the Very Large Telescope. A similar system amusing issue: local aviation. Small private planes
is being readied for the Keck II telescope. Ghez cant wait are like moths, says Marshall Perrin (Space Telescope
because she expects to see 10 times the number of stars Science Institute). Theyre drawn to the light. When
in the galactic center as shes seen before. Perrin was at Lick Observatory over a decade ago, his
Even space-based telescopes will one day utilize a team wouldnt operate the laser until 11 p.m., when most
form of adaptive optics. Though they y high above the of the general aviation was done. So-called aircraft spot-
atmosphere, their AO will correct imperfections in the ters still work today at the largest telescopes to search
optics themselves. Hubble, for example, slips between for planes.

Sk yandTelescope.com May 2016 35

 Adaptive Optics

ESO / L. CALADA / N. RISINGER (SKYSURVEY.ORG)

THE FUTURE OF AO This artists conception shows multiple lasers being deployed as part of the adaptive optics system planned
for the European Extremely Large Telescope, which is currently under construction on Cerro Armazones in Chile.

Because of these limitations some astronomers prefer lamps. The laser itself can be seen from several kilome-
using bright stars where available. Macintosh and his ters away, an eerie beam in the encompassing darkness.
colleagues, for example, only search for young planets Fugate likes to look at it philosophically. Were using
near relatively close stars, side-stepping any issues with the remnants of our solar system these meteors as
articial guide stars. But not everyone is as lucky as a mechanism to investigate the edge of the universe, he
Macintoshs team. For those who dont have a bright says. I mean, its just amazing when you think about
star handy, an articial beacon, albeit an imperfect one, how it all kind of comes together that way.
opens a new window into the universe.
So, shortly after the Sun sets, most of the biggest opti- As a freelance science journalist and former S&T intern,
cal telescopes around the world begin the nights observa- Shannon Hall spends her days pondering the wonders of
tions by ring out a laser beam the color of sodium street the universe from a local coee shop.

AO Spin-os
The ongoing quest for the perfect image doesnt stop with astronomy. Adaptive optics has also been applied
to microscopy, ophthalmology and perhaps back into the military.

Microscopy: Biological samples bend a micro- Ophthalmology: Ophthalmologists struggle Military: It took more than 25 years, but
scopes beam of light in unpredictable ways. to see past the uid inside the eye to make it seems the militarys goal to utilize laser
By rst focusing the light into a glowing point, out minute details in the retina. But with weapons has nally left the realm of science
scientists can see how it warps as it passes adaptive optics, theyre able to see the ner ction. Engineers can now pre-distort a laser
through intervening tissues and correct for features, allowing them to diagnose potential beam to cancel out atmospheric turbulence
the distortion. eye diseases early enough to prevent them. and focus with precision on a target.

36 May 2016 sky & telescope

 Investigate the Universes
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 Mercury Transit

Anom lous
Thomas Dobbins
a
Appearances How will your observations of the Mercury
transit stack up to the historical record?

Transit of Mercury

FRED ESPENAK

Amateur astronomers around the globe are making These oddities have long been the subject of specula-
preparations to observe this months transit of Mercury tion and even heated debate. Many astronomers have
(see p. 48, this issue). Passages of the tiny planet across tried to explain the mysterious black-drop eect
the face of the Sun have never stirred as much popular frequently seen when Mercurys disc touches the inner
interest as the far rarer transits of Venus, those spec- edge of the Sun at second contact (near the beginning
tacular events that have inspired expeditions to far-ung of a transit) or at third contact (near the end of a tran-
corners of the globe for several centuries. However, sit). (See S&T: Jan. 2012, p. 73.) But other strange visual
sucient attention has been paid to transits of Mercury eects have sparked interest as well. For example, the
that many anomalous appearances have been reported anomalies observed during the Mercury transit on
over the years. November 5, 1868, were the subject of a detailed account

38 May 2016 sky & telescope

in the Monthly Notices of the Royal Astronomical Society CLEARLY
written by the celebrated British amateur astronomer VISIBLE
William Huggins, who is chiey remembered today for British observer
using a spectroscope to determine the chemical com- V. A. Firso
position of stars and nebulae. A wealthy dealer in silks detected a nar-
and linen with a keen interest in the sciences, Huggins row but brilliant
used the proceeds from the sale of his familys lucrative ring around
Mercury during
textile business to build a well-equipped observatory on
the November 7,
Upper Tulse Hill in south London. Its centerpiece was
1960, transit.
a telescope that would still be the envy of most amateur He projected
astronomers a century and a half later an 8-inch the solar image

S&T: LEAH TISCIONE

refractor featuring a superb objective lens made by the from a 6.5-inch
renowned American optician Alvan Clark. reector onto a
Huggins enjoyed decent daytime seeing during the piece of white
November 1868 transit. The Suns edge was a little cardboard.
tremulous from atmospheric agitation, he recounted
in his notes, but the solar surface was so well dened A few observers interpreted the halo as sunlight
that the bright granules of which it is composed could be refracted by a dense, distended atmosphere surround-
distinctly seen. ing Mercury. Most, however, compared it to the bright
Shortly after the entire disc of Mercury was silhou- band bordering the limb of the airless Moon that had
etted against the brilliant backdrop of the Suns surface, been reported during the partial phases of solar eclipses,
Huggins noticed an even brighter, sharp-edged halo a phenomenon that Astronomer Royal George Biddell
surrounding the black dot: Airy had dismissed in 1864 as strictly an ocular nervous
phenomenon. In the 1881 edition of his classic observ-
The breadth of the luminous annulus was ing handbook Celestial Objects for Common Telescopes, the
about one-third of the planets apparent Reverend Thomas William Webb wrote o the halos as
diameter. The aureola did not fade off at deceptions from the violent contrast and the fatigue of
the outer margin, but remained of about the eye. To the French astronomer Camille Flammar-
ion, they called to mind the illusory bright aura that he
the same intensity throughout, with a defined
repeatedly saw surrounding the shadow cast by a hot air
boundary. The aureola was not sensibly
balloon onto sunlit prairies during his many ascents.
coloured, and was only to be distinguished
The halo is a striking example of a phenomenon rst
from the solar surface by a very small described by the Austrian physicist Ernst Mach in 1865.
increase of brilliancy. Mach noted that the eye-brain combination invariably
exaggerates contrasts at the borders of adjacent extended
There were a few corroborating observations of the surfaces of diering brightness. Observational astronomy
bright halo surrounding miniscule Mercury that day. is rife with examples of these Mach bands, notably the
Observing with the 12.7-inch refractor at the Royal Terby White Spot, a spurious bright feature often seen
Observatory at Greenwich, E. J. Stone reported: With bordering the intensely black shadow cast by Saturns
power 137, a ring of light was clearly visible around the globe across the planets rings (S&T: May 2014, p. 54).
disc of Mercury. It extended to a distance of nearly a But in addition to the bright halo, Huggins witnessed
semi-diameter. But scores of other observers failed to an even more curious phenomenon:
see any trace of the halo, and even Stone was cautiously
skeptical, writing: I am of the opinion that it arose from Almost at the same moment that I first
mere contrast. perceived the surrounding annulus of light, I
Similar eects had been reported for more than noticed a point of light nearly in the centre of
a century. First described by the French astronomer
the planet. This spot had no sensible diameter
Franois de Plantade in 1736, the luminous ring was
documented again by his countryman Honor Flauger-
with the powers employed [120 and 240 ],
gues during the transits of 1786, 1789, and 1799. To the but appeared as a luminous point I kept it
German astronomer Johann Hieronymus Schrter, the steadily in view until that part of the plane-
halo was a pale, almost ghostly, object that was scarcely tary disc, where the point of light was situated
brighter than the surface of the Sun. reached the Suns limb, I then ceased to see it.

Sk yandTelescope.com May 2016 39

 Mercury Transit

LUMINOUS Like the bright halo, points of light and diuse bright
ANNULUS patches were frequently reported during transit events.
British astronomer Most dispatches described features that were centrally
William Huggins located, although in some instances they were oset
reported a bright towards the edge of the planets tiny black disc.
halo surrounding
The fact that a host of observers, generally of equal
the disc of Mercury
skill and experience, and equipped with telescopes of
and a luminous
comparable size and quality, saw nothing unusual while

S&T: LEAH TISCIONE

spot on the planet
during the transit their colleagues were reporting these curious appear-
of November 5, ances was certainly troubling, and a matter of much dis-
1868. cussion. Suggestions that erupting volcanoes or intense
auroral displays might account for lights rivaling the
solar photosphere in brightness were deservedly taken
with a grain of salt. Far more plausible were the expla-
nations involving internal ghost reections from the
surfaces of the telescopes objective and eyepiece lenses,
which lacked modern antireection coatings.
In 1850, the Reverend Baden Powell, Professor
of Geometry at Oxford University and father of the
founder of the Boy Scouts, suggested that optical dif-
fraction was responsible. Eighty years later the French
astronomer and optician Andr Couder was able
to reproduce the luminous spot in his laboratory at
Meudon Observatory in Paris. While photographing
black circles projected against a brilliant background,
Couder was able to record the bulls-eye pattern of the
bright Airy disc at the center of the circle, surrounded
by faint di raction rings. A slight misalignment of the
optical elements displaced the spot toward the edge of
the circle. Even with perfectly aligned lenses, when the
background was not uniformly illuminated (to mimic
the darkening that occurs near the limb of the Sun), the
spot was not concentric.
Despite Couders convincing experiments, more than
mere optical eects seemed to be at play. Observing the
November 8, 1881, transit of Mercury through a 4.75-
inch refractor equipped with a Herschel wedge at the
Sydney Observatory, Australian astronomer Lawrence
Hargrave saw a central bright spot very distinctly three
minutes after ingress. However, he soon realized that it
would disappear on looking steadily at it. Reports like
COURTESY OF THE SCIENTIFIC PAPERS OF WILLIAM HUGGINS

Hargraves led the late William Corliss, who compiled

several catalogs of astronomical anomalies, to conclude
that something akin to those optical illusions where
grey images appear out of nowhere amid geometrical
designs might be involved.
The upcoming transit of Mercury will be an oppor-
tunity to glimpse these strange, elusive anomalies once
again. The knowledge that theyre strictly in the eye of
the beholder shouldnt rob them entirely of the ability to
evoke a sense of wonder. Through them, were visually
connected to our observing forebears.
WORKING FROM HOME Huggins poses inside his observa-
tory at Upper Tulse Hill next to the 8-inch Clark refractor kitted Contributing Editor Thomas A. Dobbins has observed most
out for spectroscopic observations. reported phenomena on the planets, both real and illusory.

40 May 2016 sky & telescope

 OBSERVING
May 2016

In This Section
42 Sky at a Glance
42 Northern Hemisphere Sky Chart
43 Binocular Highlight:
Two in the Dippers Handle
44 Planetary Almanac
45 Northern Hemispheres Sky:
The Tale of All Tails
46 Sun, Moon & Planets:
Mars Comes Closer
48 Celestial Calendar
48 The May 9th Transit of Mercury
50 Daily Jupiter Events
51 May Meteors
51 Lunar Occultation
52 Exploring the Solar System:
Lets Shoot the Moon!
54 Deep-Sky Wonders:
Get a Leg Up on Ursa Major!
Additional Observing Stories:
18 Two Cool Galaxies
38 Anomalous Appearances

This January 19, 2016 self-portrait of NASAs

Curiosity Mars rover shows the vehicle at Namib
Dune. While it looks like the rovers enjoying a
day o playing in the dirt, its actually collecting
sand samples for laboratory analysis.
PHOTOGRAPH: NASA /
JPL-CALTECH / MSSS

SkyandTelescope.com May 2016 41

 OBSERVING
Sky at a Glance Using the Map orth

MAY 2016 Go out within an hour of a time

listed to the right. Turn the map _
5 PREDAWN: The Eta Aquariid meteor shower around so the yellow label for the
peaks before dawn, but meteors should be visible direction youre facing is at the `
for several mornings before and after. This is often bottom. Thats the horizon. Above IOPEIA
a
it are the constellations in front

22 h
the best shower of the year from the Southern of you. The center of the map is M52
b
Hemisphere; see page 51. overhead. Ignore the parts of
Fa
c
the map above horizons in c
6 NIGHT: A double shadow transit occurs on Jupiter youre not facing.

M
g

39
from 9:39 to 10:42 p.m. Pacic Daylight Time. +

N
CEPH
EXACT FOR LATITUDE

E
EUS
40 NORTH.
7 EVENING: As twilight deepens, catch the thin
_
_
waxing crescent Moon as it sets. Aldebaran a

De
`
gleams about 6 upper left of the Moon.

n
M

eb
29

C
DAY: North Americans can use a telescope and

Cr rthe
9

N
g

os rn
o

Y
s
solar lter to watch the tiny dark dot of Mercury

G
N
b
cross the Sun today. The transit is visible to MINOR

M2

U
r

S
7
observers across the globe, with the exceptions of URSA

ULV
D
Australia and easternmost Asia; see page 48. R

SA

P
` A ipper

EC
C

R
Little

G
O
13 EVENING: Spot Regulus 34 above the rst-

Al
ITT

UL

bi

re
quarter Moon. Brighter Jupiter blazes some 15 to

Ve
o
`

A
a

g
a

a
LY
their upper left.
d

M5
Th

_
R
` ub

A
an
14 EVENING: Jupiter continues to reign in Leo. Find
A Q U IL
_
the bright planet about 4 upper left of the waxing

M92
60
gibbous Moon. & Alcor

/
A

HERCU
Mizar

d
2122 NIGHT: Mars reaches opposition this night in c

+
19 S E R P E N

d
Scorpius. The full Moon beams about 7 upper
h
Facing East

M13

left of the planet. M51

BOREALIS
CORONA

`
c
b

LES
22 NIGHT: The Moon rises in twilight. Look for the

a
Zenith
modest light of Saturn about 4 to its right.
_

_
IC4665

BO
30 NIGHT: Mars is closest to Earth (0.503 a.u.) and
S

_
70

M3
18.6 across, the closest and largest it has been for

T _
`
(CA

C
a

the last 10 years.

BER

ES
`
SE AP
UDA

(C b
RP UT
_
Planet Visibility
OP

Arc
SHOWN FOR LATITUDE 40 NORTH AT MID-MONTH

EN )

turu
)

M10
HI

SUNSET MIDNIGHT SUNRISE

S
_

s
M12

Hidden in the Suns glare all month

M5
UC

Mercury
VIRG
O
HU

Venus Hidden in the Suns glare all month 0

n
Moo 17
S

Mars SE S SW
c

`
L a y
Moon IB M
d

Jupiter S W May 21 R
a A
Saturn Spica _
Saturn SE S SW
`

Moon Phases Mars

b

New May 6 3:29 p.m. EDT First Qtr May 13 1:02 p.m. EDT a
S
_

/
O
M

Full May 21 5:14 p.m. EDT Last Qtr May 29 8:12 a.m. EDT
An

R
ta
Fa

/
re

P
s

S UN MON TUE WED THU FR I S AT

c

IU

g 16h
in

1 2 3 4 5 6 7 SE
S

CE
LU NT
Galaxy AU
PU RU f
8 9 10 11 12 13 14 S
Double star S e

Variable star 40
15 16 17 18 19 20 21
Open cluster
Diuse nebula 1
22 23 24 25 26 27 28
Globular cluster
Planetary nebula
29
23 30 31 Facing
30
 Gary Seronik
Facing When Binocular Highlight
1h Late March 2 a.m.*
Early April 1 a.m.* Two in the Dippers Handle
+60
ster a Late April Midnight*
Spring is galaxy season hurrah! But if youre a bin-
b
Clu ble _
CAS D u
o
US Early May 11 p.m.*
E
RS ocular user, your excitement is probably tempered by

4h
PE Late May Nightfall

the knowledge that most galaxies are bit disappoint-
W * Daylight-saving time. ing visually. Modest aperture and low power are not
N
g the ideal combination for small, dim targets. And yet,

in
even if only a few galaxies show up reasonably well in

c
Fa
lla binoculars, each is worthy of appreciation. They are,
pe
Ca after all, magnicent conglomerations of millions of

38
_
LIS

M
+80
DA stars and an unknowable number of planets. All those

36
R

M
PA
LO
suns and worlds are concentrated into a tiny fuzz of
ME dim, ancient light each one an island universe, as
CA
A

_
philosopher Immanuel Kant put it. Pretty impressive
`

Polaris

7
IG

M3
when you think about it.
R

5
M3
U

Two ne island universes are located close to the

A

+80 handle of the Big Dipper: M51 and M101. M101 is

found just above a distinctive string of stars trail-

+
k
X

M82 ing eastward from Mizar, Zeta () Ursae Majoris.

N

M81
Y

Glowing at magnitude 7.5, M101 is readily visible in

L

or

my 1545 image-stabilized binoculars, but its a real

t
Cas

_ a
f challenge in 1030s.
_

Dipper
I
b

Nearby M51 is situated in Canes Venatici and

lux

I N

Big
j
Pol

`
roughly one binocular eld southwest of Alkaid, Eta
`

b a
E M

7h
MAJOR
() Ursae Majoris the end of the Dippers handle.
Ma oon

0
y1

URSA
Listed at magnitude 8.5, you might expect it to be
M

Facing West
+
tougher to pick up than M101, and yet its not. Ive
_

CANIS MINOR
M44
`

`
even glimpsed it in 825 binoculars. How can that be?
MIN OR

Its a question of surface brightness.

CANCER

CANES
LEO

Procyon
b

_
VENATICI Both objects are face-on galaxies, which means
_

they have low surface brightness. M101 spans roughly

M67
kle

a 28 arcminutes, while M51s light is packed into a rela-

Sic
a

COMA tively compact 11-by-8-arcminute oval. That gives it

O

ola

LE

RENICES signicantly greater surface brightness magnitude

s
neb

n
ulu

oo 13
c

+20
_

13.1, verses 14.6 for M101. As a result, M51 stands out

De

Reg

M ay
M O
R better against the background glow of the night sky.
IC
`

Virgo
AT
er
M48

Galaxy T U
Cluster pit I P E Q
Ju L
C
ard
_

E
h
Alp
S

a
AN

d
XT

M101
SE

A
R
D
Y

URSA
H

b
+

US MAJOR
ie w
i

CORV
a
rv

b _
ER cu
la
20 AT o

CR 5 bin
`
_
SW

_
10h
g

c in
IA Fa
`
TL
N 1
A
0
CANES

VENATICI M51
1
13h 2
3 Star
4 magnitudes
g South
Sk yandTelescope.com May 2016 43
OBSERVING
Planetary Almanac
Mercury Sun and Planets, May 2016
May Right Ascension Declination Elongation Magnitude Diameter Illumination Distance

Sun 1 2h 33.6m +15 04 26.8 31 45 1.008

May 1 11 21 31 31 4h 32.4m +21 55 26.8 31 33 1.014

Venus Mercury 1 3h 20.8m +20 34 12 Ev +3.0 10.8 7% 0.625

11 3h 04.2m +16 49 2 Mo 12.1 0% 0.555

1 16 31 21 2h 50.6m +13 17 16 Mo +2.6 11.2 10% 0.601

31 3h 01.6m +13 13 23 Mo +0.9 9.2 27% 0.729

Mars
Venus 1 1h 57.2m +10 39 10 Mo 3.9 9.8 99% 1.697

11 2h 44.6m +14 53 7 Mo 3.9 9.7 99% 1.715

21 3h 33.7m +18 31 5 Mo 3.9 9.7 100% 1.727

1 16 31 31 4h 24.6m +21 21 2 Mo 4.0 9.6 100% 1.734
Jupiter Mars 1 16h 22.9m 21 39 153 Mo 1.5 16.1 98% 0.582

16 16h 06.2m 21 42 172 Mo 1.9 17.9 100% 0.523

31 15h 43.9m 21 23 169 Ev 2.0 18.6 100% 0.503

Jupiter 1 11h 00.0m +7 55 122 Ev 2.3 40.8 99% 4.830

31 11h 02.0m +7 36 94 Ev 2.1 37.4 99% 5.275

Saturn 1 16h 56.3m 20 49 146 Mo +0.2 18.1 100% 9.177

16 31 16h 47.8m 20 35 176 Mo 0.0 18.4 100% 9.017

Uranus 16 1h 23.0m +8 06 33 Mo +5.9 3.4 100% 20.802

Saturn
Neptune 16 22h 53.3m 7 59 74 Mo +7.9 2.3 100% 30.224

Pluto 16 19h 13.2m 20 55 128 Mo +14.2 0.1 100% 32.463

16 The table above gives each objects right ascension and declination (equinox 2000.0) at 0 h Universal Time on selected
dates, and its elongation from the Sun in the morning (Mo) or evening (Ev) sky. Next are the visual magnitude and
Uranus equatorial diameter. (Saturns ring extent is 2.27 times its equatorial diameter.) Last are the percentage of a planets disk
illuminated by the Sun and the distance from Earth in astronomical units. (Based on the mean EarthSun distance, 1 a.u.
Neptune is 149,597,871 kilometers, or 92,955,807 international miles.) For other dates, see SkyandTelescope.com/almanac.
Planet disks at left have south up, to match the view in many telescopes. Blue ticks indicate the pole currently tilted
Pluto 10"
toward Earth.

+40 2h 0h 22h 20 h 18h 16 h 14 h 12h 10 h 8h 6h 4h

RIGHT ASCENSION AURIGA
Vega Castor
+30 BOTES Pollux +30
CYGNUS
ARIES GEMINI
Venus PISCES Arcturus LEO
PEGASUS HERCULES
10
AQU ILA Regulus TA U R U S
+10 Uranus Jupiter 13 +10
Mercury OPHIUCHUS VIRGO Betelgeuse
AQU AR IU S CANCER Procyon
0 0
May 3 17 E Q U AT O R ORION
ERIDANUS 29
May L I B R A Rigel 10
Neptune
DECLINATION

10 21 22 Spica Sirius
CETUS 26
20 Pluto Saturn CORVUS H Y D R A 20
ECLIP CANIS
C APRICORNU S TIC Antares Mars MAJOR
30 Fomalhaut 30
SAGITTARIUS SC O RPIU S LOCAL TIME OF TRANSIT
40 10 am 8 am 6 am 2 am Midnight 10 pm 8 pm 6 pm 4 pm 2 pm 40
4 am

The Sun and planets are positioned for mid-May; the colored arrows show the motion of each during the month. The Moon is plotted for evening dates in the Americas when its waxing (right
side illuminated) or full, and for morning dates when its waning (left side). Local time of transit tells when (in Local Mean Time) objects cross the meridian that is, when they appear due
south and at their highest at mid-month. Transits occur an hour later on the 1st, and an hour earlier at months end.

44 May 2016 sky & telescope

OBSERVING
Fred Schaaf welcomes your
Northern Hemispheres Sky comments at fschaaf@aol.com. Fred Schaaf

The Tale of All Tails

From comets to constellations, May is the month for celestial tails.

May is a month for tails and tales about them in Comet Halley, 1986
the sky. Ill start with comet tails, but our main topic this
month is the many constellation tails that appear on the
May meridian.
Did you see a long tail on Halleys Comet 30
springs ago? In early May, 30 and 33 years ago, I
glimpsed two of the most amazing long comet tails of
my life. One belonged to the closest comet to pass Earth
in more than 200 years, Comet IRAS-Araki-Alcock. The
other belonged to the most famous of all comets, Hal-
ley. I have a request: if you saw or photographed a great
length of Halleys tail in late April or early May 1986,
please share your tale about it by contacting me.
Seven tails on the May meridian. Those 1983 and
1986 comet tails were incredibly rare sights. But every
year, we have the opportunity to observe the starry tails
of the May evening sky. No less than seven tails are

AKIRA FUJII
poised right on the skys meridian at the time of the
all-sky map at the center of this magazine, and two more
are rising. Several of these tails oer very special sights
for amateur astronomers. standing vertically beside it. But there is a less frequently
Tails of the bears, hunting dogs, and dragon. The noticed tail that sticks right between the two Bears, or
most prominent tail on the May meridian is the long one Dippers. Its the tail of Draco, the Dragon. Most of the
of Ursa Major, the Great Bear. Bears dont have long tails. famous stars and other deep-sky objects of Draco are in
How Ursa Major and Ursa Minor got one remains the dragons head and coils. But between Mizar, at the
something of a mystery. One mythic explanation is that middle of the Great Bears tail, and the Guardians of the
the tails got elongated when the bears were hurled into Pole, the two rather bright stars in the Little Bears body
the heavens by them. (Little Dippers bowl), shines Alpha () Draconis, the
The tail of Ursa Major which is also the handle of star also known as Thuban. Thuban was the North Star
the Big Dipper, Great Plough, and Celestial Wagon (see of the earliest days of Egyptian civilization a mere 4
page 24) serves as the arc to Arcturus. thousand years ago.
But the tail of Ursa Major is a fascinating sight in Many more tails for May evenings. Before the big,
itself. Test on any given night whether your naked eyes loose naked-eye Coma Star Cluster was turned into the
can see the faint star Alcor perched near the bright star hair of Queen Berenices in later Classical times, the
that forms the bend or crook in the Great Bears tail cluster represented the tuft of the tail of Leo. Its right
Mizar, itself a ne double star in almost any telescope. on the meridian this time of year. So, more or less, is the
To one side of the Great Bears tail is the sometimes tail of long, long Hydra, the Sea-Serpent.
visually elusive M101, one of the truly classic face-on spi- And there are two newly arrived tails in this months
ral galaxies. To the other side (south) of the Ursa Major sky. The front half of Scorpius, featuring Antares (and,
tail is another such galaxy, this one very prominent this May, blazing Mars!) is all thats up at our map time.
indeed. Im referring to M51, which is actually not in the But look whats just risen in the northeast and east:
bounds of Ursa Major, but rather in mostly faint Canes Cygnus, the Swan, with its rst-magnitude tail star,
Venatici the Hunting Dogs a pair of constellational Deneb (the name Deneb even means tail), and Serpens
creatures with tails (see page 43). Cauda, the tail section of the expansive two-part constel-
The May meridian also has the tail of Ursa Minor lation Serpens, the Serpent.

Sk yandTelescope.com May 2016 45

OBSERVING
Sun, Moon & Planets

Mars Comes Close

Mars gives us our closest look in a decade, while Mercury puts on a show.

This month offers two remarkable plan- ian at nightfall in May. The gas giant so too does it reach its highest altitude
etary sights that no one has seen in ten dims from magnitude 2.3 to 2.1. Its sooner; by the end of the month, it tran-
years. On May 9th Mercury passes across width shrinks from 41 to 37 but still sits the meridian around midnight.
the face of the Sun; the transit is visible displays elaborate telescopic detail in its Mars starts the month at magnitude
across all of North America. In addition, clouds during good seeing. On May 9th 1.5 and brightens until it peaks at a
Mars is coming close to Earth again. Jupiter halts its retrograde (westward) marvelous 2.1, equaling the magni-
Weve waited a decade for it to blaze motion against the starry background tude of Jupiter, for a few days late in the
brighter than magnitude 2 and appear and begins to move eastward below the month. Variations in atmospheric activity
more than 18 across in telescopes, and hindquarters of Leo. Jupiter sets around on either planet (such as planetwide dust
the time is nally here. 4 a.m. on May 1st but about 2 a.m. on storms on Mars) can alter brightness by
In early May, brilliant Jupiter is the only May 31st, so its no longer a dusk-to-dawn as much as a few tenths of a magnitude,
planet visible at dusk. But as the month attraction at the end of the month. so compare the two planets when theyre
progresses, ery Mars rises earlier and Mars arrives at its best opposition in at similar altitudes.
earlier after sunset, until it nally shines 11 years on May 22nd. Due to the con- The view of Mars with the naked eye
as twilight falls, rivaling Jupiter in bright- siderable ellipticity of its orbit, Mars can or in binoculars this month is captivat-
ness. Zero-magnitude Saturn comes up reach its closest approach to Earth quite a ing. In a telescope, it appears just 16
soon after Mars, sharing its company with few days before or after opposition. This wide as the month opens, but reaches a
1st-magnitude Antares in Scorpius. Mer- year is a case in point, as closest approach maximum angular diameter of 18.6 at
cury is only easily visible this month on doesnt happen until May 30th. the end of May. Thats large enough to
May 9th, when it transits the Sun. Venus Fire-colored Mars rises two hours after reveal numerous surface markings with a
is lost in the solar glare all month. sunset as May opens, but its rapid retro- good telescope under good seeing condi-
grade motion brings it up right at sunset tions. To determine which side of Mars
DUSK TO DAWN by May 22nd. On May 1st, the Red Planet and which surface features face you at
Jupiter shines at its highest in the south, shines highest after 2:30 a.m. daylight- any given time, use the S&T Mars Proler
coming into view not far from the merid- saving time. As it begins to rise earlier, (http://is.gd/marsproler). See our Mars
observing guide in last months issue,
page 48, as well.
Dawn, May 7 aGem Dusk, May 79 Mars spends the month retrograding
1 hour before sunrise 45 minutes after sunset
across the narrow, northward-extending
Moon
strip of western Scorpius. It begins May
May 9
` some 5 north of Antares and threads
Saturn
c the gap between Beta () and Delta ()
10 Scorpii on the 19th. At opposition on the
Mars 22nd, it comes very close to Delta. But
Betelgeuse
Antares
rapid retrograde motion simultaneously
Moon
May 8 carries Mars toward Libra, away from the
Cats
Eyes TA U R U S These scenes are drawn for near the middle of
SCORPIUS
North America (latitude 40 north, longitude
Aldebaran 90 west); European observers should move
Moon each Moon symbol a quarter of the way toward
May 7 the one for the previous date. In the Far East,
move the Moon halfway. The blue 10 scale bar
is about the width of your st at arms length.
Looking South-Southwest Looking West For clarity, the Moon is shown three times its
actual apparent size.

46 May 2016 sky & telescope

To nd out whats visible in the sky from your location, go to skypub.com/almanac. Fred Schaaf

December
solstice

O R B IT S O F THE P L ANE T S Venus

The curved arrows show each planets movement
March Sun Sept.
during May. The outer planets dont change position equinox Mercury equinox
enough in a month to notice at this scale.
Earth
Mars
much more slowly retrograding planet June solstice
just over the border in Ophiuchus
ringed Saturn.
Saturn rises about 30 minutes after
Mars on May 1st but trails its planetary
neighbor by about an hour at months Jupiter Uranus
end. While Mars brightens by more than
half a magnitude over the course of the Saturn Neptune
month, Saturns radiance improves only
slightly, from +0.2 to 0.0. As May ends,
when Mars is closest to Earth, the equato- Pluto
rial diameter of Saturns globe has grown
to 18.4 almost exactly the same size
as Mars in your telescope! But the surface
of Saturn is much dimmer, due to its 7
times greater distance from the Sun. DAWN MOON PA SSAGES
The rings of Saturn, tilted 26 from Mercury transits the Sun on May 9th; At dusk on May 7th, the thin crescent
edge-on, span an even greater length: 42 see page 48. Other than this, the tiny Moon appears very low with Aldebaran
this month. The ringed world is headed planet remains almost too dim and low above it. The waxing gibbous Moon
for opposition on the night of June 2nd. to see emerging before sunrise even at shines near Regulus on the evening of
Saturn forms a triangle with Mars and months end. Venus is headed for supe- May 13th and near Jupiter on the 14th.
Antares all month. Watch the triangle rior conjunction on June 6th and is not On the night of May 21st, the full Moon
elongate as time passes. May begins with visible in May. forms a near-rectangle 10 long with
Mars and Saturn 8 apart and ends with Pluto, in northern Sagittarius, reaches Mars, Saturn, and Antares. The next
them separated by 15. Meanwhile slow, the meridian before dawn begins. Nep- evening, the Moon rises left of Saturn.
distant Saturn stays nearly on station tune and Uranus are poorly placed for On the morning of 25th, the Moon poses
with xed Antares. observation this month. above the teapot of Sagittarius.

Dusk, May 13 15 May 20 22 Dawn, May 24 26

45 minutes after sunset Around 10 pm 1 hour before sunrise
Moon
Moon
May 26
Sickle May 20 Moon
a
May 25

` Moon
Mars May 24
Moon
Regulus May 21 b

 Jupiter

Moon
Saturn S A G I T TA R I U S
Moon Antares
May 13 Moon
Moon May 14
May 15
May 22 SCORPIUS

Looking South, high up Looking Southeast Looking South-Southwest

Sk yandTelescope.com May 2016 47

OBSERVING
Celestial Calendar

The May 9th Transit of Mercury

The littlest planet will cross the enormous Sun for viewers in most of the world.

Mark Monday May 9th on your calendar. As the

Sun crosses the sky that day, Mercury will cross the
face of the Sun for the rst time since 2006.
If youre in western North America, the rising
Sun will already display Mercurys telltale black
dot, as indicated on the world map at right. Eastern-
ers and many Western Europeans will be able to
watch the entire transit, weather permitting, from
Mercurys rst nudge into the Suns face to its nal
slide-away 7 hours later.
For the rest of Europe, Africa, and most of Asia,
the transit also begins in the daytime but will still
be underway when the Sun sets. Folks in Australia
and eastern Asia will just have to watch online.
The timetable below tells when the rst edge
of Mercury enters the Sun and the last edge leaves
(rst and last contact), in Universal Time and in
civil daylight-saving times for North America.
Times of the events will dier by a few minutes as
seen from various locations on Earth.
If you dont have a safe white-light solar lter that
mounts over the front of your telescope, nows the
time to get one. Theyre available from astronomy
dealers in many sizes and ts. When we reviewed
them, we liked the ones made with Baader Astro-
Solar aluminized polyester the best (S&T: Feb. 2005,
Mercury in transit appears tiny, but unlike sunspots, its round and has no
penumbra. It moves noticeably in 15 minutes, the average time between these p. 102, and July 1999, p. 63). This material is opti-
exposures taken by Dominique Dierick during the transit of May 7, 2003. cally superb despite its wrinkly appearance, and it
leaves the Sun a fairly natural color.
DOMINIQUE DIERICK Alternatively, you can use an unltered telescope
Transit Timetable with your lowest-power eyepiece to project an image
of the Suns disk onto white paper a foot or two
Time Zone Transit Begins Transit Midpoint Transit Ends behind the eyepiece, and watch the events transpire
Universal (GMT) 11:12 14:58 18:42 on the paper. But a direct view through a solar
lter shows the scene better. (Of course, never look
Eastern (EDT) 7:12 a.m. 10:58 a.m. 2:42 p.m.
directly at the Sun without a proper lter.)
Central (CDT) 6:12 a.m. 9:58 a.m. 1:42 p.m. And yes, you do need the telescope. Mercury is
Mountain (MDT) 5:12 a.m. 8:58 a.m. 12:42 p.m.
the smallest planet. Its black silhouette will appear
only 10 arcseconds wide even though Mercury is at
Pacic (PDT)* 7:58 a.m. 11:42 a.m. inferior conjunction. Thats about 00 of the Suns
Alaskan (AKDT)* 6:58 a.m. 10:42 a.m. width, and only a sixth the diameter (and 3% of the
area) of Venuss dramatic black disk during the rare
Hawaiian (HST)* 8:42 a.m.
transits of Venus. At rst glance you might mistake
Times for your location may dier by several minutes. *Transit begins before sunrise. Mercury for a small sunspot but look again. Its
precisely round and lacks a gray penumbra.

48 May 2016 sky & telescope

 Learn how to use detailed star charts to nd the faintest things
that your telescope can show: skypub.com/charts. Alan MacRobert

Most of the inhabited

world will be able to
see at least part of
the transit, weather
permitting. Observ-
Entire
Entire ers in eastern North
transit
transit
visible America and western
visible
Europe can watch
both the entry and
exit of Mercury across
the Suns edges.

Transit
Transit Transit
Transit No
in progress
in progress in progress
in progress transit
at sunrise
at sunrise at sunset
at sunset visible

Transit of Mercury
May 9, 2016
Eclip
tic

Mercury E W
12 h UT Path of
moves Mercur
onto Sun 15 h UT y
If youre in the Americas, dont miss the chance
7:12 a.m. EDT 18 h UT
to watch tiny Mercury slip o the Sun. Be Transit
watching by about 18:35 UT (2:35 p.m. Eastern midpoint
14:58 UT Mercury
Daylight Time). Can you see anything of the
leaves Sun
FRED ESPENAK

black drop eect as Mercury begins to contact 2:42 p.m. EDT

the Suns limb?

And it moves! The most interesting aspects to watch of phenomena at ingress unwinds in reverse order.
will be Mercury making its entrance and/or exit across Although transits of Mercury are less dramatic than
the Suns limb. The planet will take 3 minutes and 12 those of Venus, they come more often. The last two
seconds to do so. If you can watch at the time of ingress, Venus transits happened in 2004 and 2012 after a gap
keep your eye on the limb barely south of due east for the since 1882, and not until 2117 will the world see another.
rst detectable sign of a tiny dent. Use high power. You But Mercury passes between the Earth and Sun about 13
can tell which limb is celestial east by turning o your or 14 times every century. It will next do so on November
telescopes drive if it has one; the Sun will drift across 11, 2019 again visible from the Americas and Europe.
the eyepiece view from east to west. There are a couple of reasons for the dierence.
At second contact when Mercurys trailing edge Mercury rounds the Sun more frequently than Venus
comes onto the Sun watch for any sign of the black does and passes through inferior conjunction ve times
drop eect: the illusory appearance of a tiny black line still as often. And Mercury is also closer to the Sun, so from
connecting the planet to the outer darkness. And does Mercury, the Sun presents a larger target for a line of
the black disk show a central point of light? More about sight from Earth through the planet to hit.
such anomalous appearances begins on page 38. As youre watching the transit, imagine a copy of
As Mercury travels across the Suns vast expanse, how Earth replacing Mercury. It would look only 2.6 times
readily can you see its motion? If it passes near a sun- wider than the tiny dot a reminder of how insigni-
spot, can you see that its darker than even the sunspots cant the terrestrial worlds appear next to the awesome
umbra? When Mercury departs at egress, the sequence scale of our home star.

Sk yandTelescope.com May 2016 49

OBSERVING
Celestial Calendar
Jupiters Moons Daily Jupiter Events
May 1 Jupiters Great
Red Spot is
2
living up to its
3 EAST WEST name better than
at any time in
4 memory. In a
5 small telescope,
its much less dif-
6 cult to see now.
7 Christopher Go
shot this stacked-
Io
8 video image on
January 4th using
9
a 14-inch scope.
10 South is up.

11 Europa

CHRISTOPHER GO
12

13

14
Telescope users in May should plan 12:01, 21:57; 24, 7:52, 17:48; 25, 3:44, 13:39,
15 Ganymede to catch Jupiter right around the end 23:35; 26, 9:31, 19:27; 27, 5:22, 15:18; 28,
16 of twilight, while its still high on the 1:14, 11:09, 21:05; 29, 7:01, 16:56; 30, 2:52,
meridian or just past it. 12:48, 22:44.
17
Jupiters four big Galilean moons are May 1, 8:39, 18:35; 2, 4:31, 14:26; 3, 0:22,
18 visible in any scope. Binoculars usually 10:18, 20:14; 4, 6:09, 16:05; 5, 2:01, 11:56,
show at least two or three. Identify 21:52; 6, 7:48, 17:44; 7, 3:39, 13:35, 23:31; 8,
19
them using the diagram at left. 9:26, 19:22; 9, 5:18, 15:14; 10, 1:09, 11:05,
20 All of Mays interactions between 21:01; 11, 6:57, 16:52; 12, 2:48, 12:44, 22:39;
21
Jupiter and its satellites and their shad- 13, 8:35, 18:31; 14, 4:27, 14:22; 15, 0:18, 10:14,
ows are listed on the facing page. On 20:10; 16, 6:05, 16:01; 17, 1:57, 11:53, 21:48;
22 Friday night May 67, North Americans 18, 7:44, 17:40; 19, 3:36, 13:31, 23:27; 20,
23 can watch a double shadow transit: both 9:23, 19:19; 21, 5:14, 15:10; 22, 1:06, 11:02,
Callisto and Io are casting their tiny 20:57; 23, 6:53, 16:49; 24, 2:45, 12:40, 22:36;
24 Callisto black shadows onto Jupiter from 4:39 to 25, 8:32, 18:28; 26, 4:23, 14:19; 27, 0:15,
25 5:42 May 7th UT. (To get Eastern Day- 10:11, 20:07; 28, 6:02, 15:58; 29, 1:54, 11:50,
light Time, subtract 4 hours from UT.) 21:45; 30, 7:41, 17:37; 31, 3:33, 13:29, 23:24.
26
And here are all the times, in Uni- These times assume that the Great
27 versal Time, when Jupiters Great Red Red Spot is centered at System II lon-
Spot unusually vivid this year! gitude 234. It will transit 12/3 minutes
28
should cross the planets central merid- earlier for each degree less than 234,
29 ian. The dates, also in UT, are in bold. and 12/3 minutes later for each degree
30 April 1, 3:56, 13:51, 23:47; 2, 9:42, 19:38; 3, greater than 234. Features on Jupiter
5:34, 15:29; 4, 1:25, 11:21, 21:16; 5, 7:12, 17:08; appear closer to the central meridian
31 6, 3:03, 12:59, 22:54; 7, 8:50, 18:46; 8, 4:41, than to the limb for 50 minutes before
14:37; 9, 0:33, 10:28, 20:24; 10, 6:20, 16:15; and after transiting.
11, 2:11, 12:07, 22:02; 12, 7:58, 17:54; 13, 3:49, A light blue or green lter slightly
The wavy lines represent Jupiters four big satellites. The central 13:45, 23:41; 14, 9:36, 19:32; 15, 5:28, 15:23; increases the contrast and visibility of
vertical band is Jupiter itself. Each gray or black horizontal band is
16, 1:19, 11:15, 21:10; 17, 7:06, 17:02; 18, 2:57, Jupiters reddish and brownish mark-
one day, from 0h (upper edge of band) to 24h UT (GMT). UT dates
are at left. Slide a papers edge down to your date and time, and 12:53, 22:49; 19, 8:44, 18:40; 20, 4:36, 14:31; ings. An orange lter helps to darken
read across to see the satellites positions east or west of Jupiter. 21, 0:27, 10:23, 20:18; 22, 6:14, 16:10; 23, 2:05, the blues.

50 May 2016 sky & telescope

For how to make a scientic meteor count, see imo.net/visual/major.

May Meteors Phenomena of Jupiters Moons, May 2016

May 1 2:18 I.Ec.R 1:21 I.Sh.E 12:51 III.Oc.D May 24 1:01 III.Ec.R
Only one major meteor stream, the one
20:09 I.Tr.I 1:26 II.Oc.D 16:13 III.Oc.R 2:32 I.Ec.R
shed by Halleys Comet, intersects Earths 21:13 I.Sh.I 17:50 III.Ec.D
6:28 II.Ec.R 20:12 I.Tr.I
orbit in two places with both of the result- 22:24 I.Tr.E 9:06 III.Oc.D 21:03 III.Ec.R 21:26 I.Sh.I
ing showers being visible at night. In Octo- 23:01 II.Oc.D 12:27 III.Oc.R 21:08 I.Oc.D 22:26 I.Tr.E
ber we call them the Orionids, and in May 23:27 I.Sh.E 13:51 III.Ec.D May 17 0:37 I.Ec.R 23:39 I.Sh.E
theyre the Eta Aquariids. May 2 3:53 II.Ec.R 17:04 III.Ec.R 18:19 I.Tr.I May 25 1:24 II.Tr.I
Both showers run for several days and 5:24 III.Oc.D 19:16 I.Oc.D 19:31 I.Sh.I 3:57 II.Sh.I
have a reputation for meteors that are 8:45 III.Oc.R 22:42 I.Ec.R 20:34 I.Tr.E 4:12 II.Tr.E
swift and relatively faint. But in May we 9:50 III.Ec.D May 10 16:27 I.Tr.I 21:45 I.Sh.E 6:40 II.Sh.E
apparently pass nearer to the center of the 13:05 III.Ec.R 17:36 I.Sh.I 22:51 II.Tr.I 17:29 I.Oc.D
17:25 I.Oc.D May 18 1:20 II.Sh.I 21:01 I.Ec.R
stream; the Eta Aquariid shower is roughly 18:42 I.Tr.E
20:46 I.Ec.R 19:50 I.Sh.E 1:39 II.Tr.E May 26 14:40 I.Tr.I
three times as strong as the Orionid
May 3 14:37 I.Tr.I 20:20 II.Tr.I 4:04 II.Sh.E 15:54 I.Sh.I
shower, and it lasts longer too.
15:41 I.Sh.I 22:43 II.Sh.I 15:36 I.Oc.D 16:55 I.Tr.E
This year the Eta Aquariids should peak 16:51 I.Tr.E 19:05 I.Ec.R
23:08 II.Tr.E 18:08 I.Sh.E
on the mornings of May 5th and 6th, when 17:52 II.Tr.I May 19 12:47 I.Tr.I 19:40 II.Oc.D
May 11 1:27 II.Sh.E
they will be untroubled by moonlight. This 17:56 I.Sh.E 13:59 I.Sh.I May 27 0:55 II.Ec.R
13:44 I.Oc.D
is usually the best shower of the year for 20:06 II.Sh.I 15:02 I.Tr.E 6:32 III.Tr.I
17:10 I.Ec.R
the Southern Hemisphere, with perhaps 20:39 II.Tr.E 16:13 I.Sh.E 9:51 III.Tr.E
May 12 10:55 I.Tr.I
60 meteors visible per hour before dawn to 22:51 II.Sh.E
12:05 I.Sh.I
17:09 II.Oc.D 11:39 III.Sh.I
an observer under ideal conditions. Meteor May 4 11:52 I.Oc.D
13:10 I.Tr.E
22:20 II.Ec.R 11:57 I.Oc.D
watchers in northern latitudes see fewer, 15:15 I.Ec.R May 20 2:40 III.Tr.I 14:48 III.Sh.E
14:19 I.Sh.E
and those north of 40 or 45 see hardly May 5 9:04 I.Tr.I
14:40 II.Oc.D
5:59 III.Tr.E 15:29 I.Ec.R
10:10 I.Sh.I 7:40 III.Sh.I May 28 9:08 I.Tr.I
any, because the showers radiant (at the 19:45 II.Ec.R
11:19 I.Tr.E 10:04 I.Oc.D 10:23 I.Sh.I
Water Jar, the head of Aquarius) is still low 22:52 III.Tr.I
12:13 II.Oc.D 10:50 III.Sh.E 11:23 I.Tr.E
in the east-southeast as dawn brightens. May 13 2:10 III.Tr.E
12:24 I.Sh.E 13:34 I.Ec.R 12:37 I.Sh.E
On the other hand, when a showers 17:11 II.Ec.R
3:40 III.Sh.I
May 21 7:15 I.Tr.I 14:41 II.Tr.I
radiant is low, the few meteors that do 19:09 III.Tr.I
6:51 III.Sh.E
8:28 I.Sh.I 17:15 II.Sh.I
appear will be long, dramatic Earthgrazers, 22:27 III.Tr.E
8:11 I.Oc.D
9:30 I.Tr.E 17:28 II.Tr.E
sometimes ying far across the sky (S&T: 11:39 I.Ec.R
23:41 III.Sh.I 10:42 I.Sh.E 19:58 II.Sh.E
Aug. 2014, p. 64). May 6 2:53 III.Sh.E
May 14 5:23 I.Tr.I
12:07 II.Tr.I May 29 6:26 I.Oc.D
6:33 I.Sh.I
6:20 I.Oc.D 14:38 II.Sh.I 9:58 I.Ec.R
7:38 I.Tr.E
9:44 I.Ec.R 14:54 II.Tr.E May 30 3:37 I.Tr.I
8:47 I.Sh.E
Lunar Occultation 16:29
19:31
IV.Tr.I
IV.Tr.E 9:35 II.Tr.I May 22
17:22
4:32
II.Sh.E
I.Oc.D
4:52
5:52
I.Sh.I
I.Tr.E
If youre out observing the May 7 3:18 IV.Sh.I 12:01 II.Sh.I 8:03 I.Ec.R 7:05 I.Sh.E
Moon with a telescope late on the 3:32 I.Tr.I 12:23 II.Tr.E May 23 1:43 I.Tr.I 8:57 II.Oc.D
night of May 1718, you may notice 4:39 I.Sh.I 14:45 II.Sh.E 2:57 I.Sh.I 14:13 II.Ec.R
May 15 0:05 IV.Oc.D
that its dark limb is creeping toward 5:42 IV.Sh.E 3:58 I.Tr.E 20:35 III.Oc.D
5:47 I.Tr.E 2:40 I.Oc.D 5:11 I.Sh.E 23:57 III.Oc.R
a 4.4-magnitude star: Theta Virginis.
6:53 I.Sh.E 3:14 IV.Oc.R 6:24 II.Oc.D May 31 0:55 I.Oc.D
The Moon will go on to occult the
7:05 II.Tr.I 6:08 I.Ec.R 9:18 IV.Tr.I 1:48 III.Ec.D
star for viewers all across North 12:00 IV.Ec.D
9:24 II.Sh.I 11:38 II.Ec.R 4:27 I.Ec.R
America, although for easterners 9:53 II.Tr.E 14:17 IV.Ec.R 12:28 IV.Tr.E 4:59 III.Ec.R
the Moon and star will be getting 12:09 II.Sh.E 23:51 I.Tr.I 16:41 III.Oc.D 17:23 IV.Oc.D
low in the west. May 8 0:48 I.Oc.D May 16 1:02 I.Sh.I 20:03 III.Oc.R 20:38 IV.Oc.R
Some disappearance times: at 4:13 I.Ec.R 2:06 I.Tr.E 21:22 IV.Sh.I 22:05 I.Tr.I
Washington, DC, 3:23 a.m. EDT; 22:00 I.Tr.I 3:16 I.Sh.E 21:49 III.Ec.D 23:20 I.Sh.I

Chicago, 2:10 a.m. CDT; Denver, 23:07 I.Sh.I 3:54 II.Oc.D 23:01 I.Oc.D
May 9 0:14 I.Tr.E 9:03 II.Ec.R 23:34 IV.Sh.E
12:51 a.m. MDT; Los Angeles, 11:36
p.m. PDT. Detailed local timetables Every day, interesting events happen between Jupiters satellites and the planets disk or shadow. The rst columns give the date and
for both the disappearance and mid-time of the event, in Universal Time (which is 4 hours ahead of Eastern Daylight Time). Next is the satellite involved: I for Io, II
Europa, III Ganymede, or IV Callisto. Next is the type of event: Oc for an occultation of the satellite behind Jupiters limb, Ec for an
reappearance of the star are at
eclipse by Jupiters shadow, Tr for a transit across the planets face, or Sh for the satellite casting its own shadow onto Jupiter. An
is.gd/ThetaVirMay2016. occultation or eclipse begins when the satellite disappears (D) and ends when it reappears (R). A transit or shadow passage begins at
ingress (I) and ends at egress (E). Each event is gradual, taking up to several minutes. Predictions by IMCCE / Paris Observatory.

Sk yandTelescope.com May 2016 51

 OBSERVING
Exploring the Solar System

Lets Shoot the Moon!

Its easy to take high-quality images of the lunar disk.

The digital imaging revolution has taken astronomy the manual setting, you can adjust the shutter speed,
by storm. Spectacular images recorded by amateurs exposure, aperture, and ISO (or at least your phones
using digital single-lens reex (DSLR) cameras, spe- brightness setting) to control the amount of light reach-
cialized planetary cameras, and large-format CCDs ing the cameras detector. A fast shutter speed helps
dominate the pages of this magazine. But the imaging minimize blurriness due to atmospheric turbulence,
devices you most likely own are smartphones, tablets, and wind, a nontracking mount, or an unsteady hand hold-
compact point-and-shoot cameras. Surprisingly, these ing the camera up to the eyepiece.
simple devices are capable of producing pretty, even Perhaps the most important setting is ISO. Basically,
stunning images of our nearest neighbor, the Moon. Its the higher the ISO value, the greater the detectors sensi-
not quite as easy as just walking up to the eyepiece and tivity to light. Typical smartphones or compact cameras
snapping away but thats the general idea. have an ISO range of 100 to 1600, while new low-light
Whether you have a smartphone or tablet (which models can reach 6400, 12,800, or higher. The tradeo
usually have small, xed-focus lenses) or a much more is that higher ISOs add more noise or graininess in
versatile compact camera or DSLR, all employ a similar the image. Try using 200 or 400, at least to start, for the
set of operational modes. Some have a manual setting, greatest dynamic range and lowest image noise.
and thats preferable to the automatic mode, which The beauty of lunar imaging is that even a small
tends to overexpose lunar images. Apps like NightCap 60-mm refractor or 4-inch reector can produce stun-
Pro can add these features to your smartphone. Using ning images. Aperture isnt a major factor, as the camera
is using the telescope as a giant telephoto lens. This
optical arrangement telescope, eyepiece, and a camera
with an attached lens is called afocal photography.
While unguided telescopes can produce nice results, a
telescope thats tracking the Moon will generally produce
better, less blurry images. If you have a steady hand,
then just center the cameras lens over the eyepiece and
use the self-timer function to secure decent images.
However, to get the sharpest images and best resolu-
tion, some mechanical help will come in handy. Almost
indispensable for basic astro-imaging is a good photo tri-
pod. Most cameras have a -20 threaded hole for attach-
ing it, or you can purchase an inexpensive tripod adapter
for your smartphone. (In fact, most sele sticks
employ a simple yet eective tripod adapter.) If tripods
arent your style, then get a smartphone or compact-
camera adapter that clamps onto the focusing tube and
positions the camera lens directly over the eyepiece.
Technology oers alternatives to using the self-timer
approach. Perhaps your camera can be used with a
mechanical or electronic remote release. With some
cameras a wireless Bluetooth controller can trip the
shutter from up to 30 feet away.
HARRISON MCGAHA

Equipped with only a 4-inch reector and modest Canon PowerShot

A530 camera, 13-year-old Harrison McGaha snapped this excellent view of Now Lets Go Image!
a gibbous Moon last August from his home in Chelsea, Alabama. Its time to put your equipment and technique to practice
by doing some lunar imaging. Before you head outside,

52 May 2016 sky & telescope

Frequent contributor Richard Jakiel observes everything
from the nearby Moon to distant galaxies. Richard Jakiel

S&T: SEAN WALKER (2)

RICHARD JAKIEL (2)

Left: By purchasing an adjustable adapter, you can attach a smartphone or small digital camera directly to a telescopes eyepiece.
Right: Compare the detail and contrast in these lunar images taken with a smartphone (left) and a point-and-shoot digital camera (right).

however, make sure the camera lens is clean and that the in a wide variety of situations. For example, you can cap-
largest possible image le is selected. Make sure your ture faint Earthshine on the darkened lunar disk when
battery is charged and turn o the ash! the Moon is near new. Or record its sequence of phases
Point your telescope at the Moon, focus the eyepiece, over an entire lunar cycle. Not only will you learn how
and then position the camera lens directly over the the surface brightness changes with phase, but youll
eyepiece. Make sure its pointing straight in, not tilted, also have an impressive photo mosaic once the project
to minimize distortion. Now use the telescopes focuser is completed. The bottom line: dont be afraid to experi-
to produce a crisp image onto the cameras display. Go ment, have fun, and go shoot lots of images!
with low-power eyepieces, which tend to have larger
eld lenses and good eye relief. This makes centering
M O R E LU N A R - IMAG IN G TIP S
the Moon easier and reduces vignetting (reduced image
For an expanded version of this article, go to http://is.gd/
brightness) around the frames periphery.
basic_lunar_imaging. To learn about advanced lunar-im-
If possible, try not to use the automatic-exposure aging techniques, see Robert Reeves guide on page 66.
mode, as this tends to under- or overexpose the image.
(That said, its easier to bring out detail in an under-
exposed image via computer processing.) A technique
called bracketing works particularly well with lunar
The Moon May 2016
imaging. By shooting many images over a wide range
10
of exposures and ISOs, you can accommodate the huge Phases
brightness range of lunar features and work around any NEW MOON
blurring induced by atmospheric turbulence. May 6, 19:30 UT
While capturing images, use the smartphones FIRST QUARTER
display or the cameras live-screen view to check your May 13, 17:02 UT
framing and focus. You can experiment with the cam- May 1
NASA / LRO

FULL MOON
eras optical zoom, if its got one, to capture the small- May 21, 21:14 UT 25
est surface details, though changing to a higher-power LAST QUARTER
eyepiece can work just as well. But dont use the digital May 29, 12:12 UT For key dates, yellow dots indicate
which part of the Moons limb is
zoom smartphone users, take note! because that tipped the most toward Earth by
doesnt actually record ner details. libration under favorable illumination.
Finally, shooting lots of images is a good hedge
against things that go bump in the night. Almost Distances Favorable Librations
anything that can go wrong often will ranging from Perigee May 6, 4h UT Lacus Veris May 1
knocking the telescope o target to losing focus, vignett- 357,827 km diam. 33 23 Hayn (crater) May 10
ing, weird internal reections, power loss, and unex- Apogee May 18, 22h UT Montes Rook May 25
pected weather changes. 405,933 km diam. 29 26
Even a basic camera is capable of shooting the Moon

Sk yandTelescope.com May 2016 53

OBSERVING
Deep-Sky Wonders

Get a Leg Up on Ursa Major!

Take advantage of the Big Bears wealth of galaxies this month.

Ursa Major, the Big Bear, is the third largest constel- Ursa Majors last leg is rooted to her body at the star
lation in the sky, surpassed only by Hydra and Virgo. Gamma () Ursae Majoris, commonly known as Phecda
Because it also oers us a clear window to the uni- or Phad, meaning thigh. From there the leg stretches
verse beyond our Milky Way, Ursa Major is home to a through Chi () to the Bears toes at Nu () and Xi ().
mind-boggling number of galaxies. In the New General The spiral galaxy Messier 109 dwells 39 east-
Catalogue (NGC) alone, there are 394 galaxies that call southeast of Phecda within a distinctive trapezoid of
the constellation home. Observing them all is a daunting stars, magnitudes 8.6 to 9.7. The trapezoids three-star
task for backyard stargazers, so lets embark on a more base is 25 west of its two-star top. With 1545 binocu-
casual exploration, limiting ourselves to a few in the lars and averted vision, I can make out a very faint, oval
region of the Big Bears hindmost leg. glow cuddled up to the middle star in the base. M109
reveals a small, brighter center and tiny core through my
130-mm refractor at 63. The middle star and a dimmer
companion watch over the galaxys west-southwestern
end, while a faint star closely guards the opposite tip.
Two faint stars pop out along M109s north-northwestern
side at 117, and the galaxys bright center is elongated
and skewed with respect to its halo. Through my 10-inch
scope at 166, M109 segregates into halo, bar, core, and
nucleus as captured on my pencil sketch below.
Although this galaxy is accorded the designation M109,
Charles Messiers last published catalog (1781) listed only
103 objects. Seven were later added by others, based on
evidence that either Charles Messier or his friend and col-
M109
league Pierre Mchain observed them. By 1947 the list had
grown to include M107. Then Owen Gingerich of Harvard
College Observatory proposed two new candidates from
objects briey mentioned in Messiers description of M97
(S&T: Sept. 1953, p. 288). From the description and Ging-
erichs study of the region, he unambiguously identied
one as NGC 3556, now dubbed M108. With the addition
of a personal notation penned by Messier, the other was
shown to be NGC 3992, now M109.

N
MASIL IMAGING TEAM

Imaged here with a 12.5-inch f/3.93 astrograph for a total exposure of Modest aperture displays M109 as an oblong
9 hours, the nearly face-on barred spiral galaxy M109 sports a bright fuzzy spot, but the author was able to resolve
central region with bar as well as distinct arms. the galaxys halo, bar, core, and nucleus with
her 10-inch reector at 166.

54 May 2016 sky & telescope

Sue French welcomes your comments at scfrench@nycap.rr.com. Sue French

Sweeping 1.5 east-southeast from M109 carries us to 4. Averted vision makes the galaxys faint tips stand out
NGC 4102. Through my 130-mm scope at 23, this spiral well, drawing this milky splinter of light out to nearly 6.
galaxy is small but easily visible southeast of an 8.0-magni- NGC 4085 also takes on character, becoming a junior ver-
tude star. Using averted vision I can spot the irregular gal- sion of the Whale Galaxy (NGC 4631 in Canes Venatici).
axy NGC 4068 in the same eld of view, 23 west-south- This trio of galaxies, as well as M109 and NGC 4102,
west of its neighbor, with two faint yet distracting stars to are all members of the M109 Group, centered about 60
its west. NGC 4068 shows well at 37, its pale countenance million light-years away from us.
tipped northeast. The glint of a nearly central, superim- NGC 4085 hovers a few arcminutes north of an east-
posed star smartens the galaxy, and the western stars are west pair of stars, magnitudes 8.2 and 8.6. If we plunge
joined by a third to form a shallow arc. NGC 4102 appears 2.8 due south from the eastern star, well come to NGC
oval and leans in the same direction as its companion.
It harbors a bright, oval core and wears a faint star on its 12h 10m 12h 00m
west-southwestern fringe. At 63 NGC 4102 covers about +51
2 1. Roughly one-third those dimensions, the galaxys 4026
luminous core intensies toward its center. 4088
Although these galaxies look about the same size on 4157
4085
the sky, NGC 4068 is a dwarf galaxy thats much closer URSA MAJOR
to us than NGC 4102, shining at us from distances of +50
approximately 15 million and 62 million light-years,
Star magnitudes

7
respectively. Perhaps we should refer to NGC 4068 as 4100
8
a Starbird, for its inclusion in the panchromatic STAR- 9
Burst IRregular Dwarf Survey (STARBIRDS), intro- 10
duced by Kristen McQuinn and colleagues in a 2015 11 +49
paper in the Astrophysical Journal Supplement Series.
The multi-wavelength study seeks to shed light on star
formation in these galaxies, which occurs in intense epi-
sodes that can last more than a hundred million years. 12h 30m 12h 20m 12h 10m 12h 00m 11h 50m 11h 40m 11h 30m +54
Now well drop south to the spiral-galaxy trio NGC
4088, NGC 4085, and NGC 4157. NGC 4088 is bright 3 M109
Star magnitudes

even in my 130-mm refractor at 23. It extends northeast- 4 4102 URSA MAJOR

southwest and hosts a brighter center. At 63 NGC 4085 5 4068
+52
joins the scene, faintly visible 11 south of its partner as a 6 3953
7 5
slender, ashen glow that leans a bit north of east. Pushing
8
the telescope 53 east brings NGC 4157 into the eld of 4026
view. This moderately faint but pretty galaxy is long and 4088
CANES 4157
svelte, with a 10th-magnitude star punctuating its west- VENATICI 4085 +50
southwestern tip. The galaxy brightens toward its center
4100
and its long axis, a trait NGC 4085 shares when I boost 3
the magnication to 91. NGC 4085 then appears about 2 3893
long and one-fourth as wide, but its eastern end is wider +48
4220
3949

than its western end. NGC 4088 measures about 3 long
M106
and one-third as wide, with a brighter, elongated center. 4096
3877
3726
To me, the galaxy seems rather pointy at its northeastern 4346 4217
end. At 117 NGC 4088 shows hints of spiral structure 4144
+46
forming a pattern like a Z or S that someone stepped on.
4242
The shape of NGC 4088 is quite remarkable through
my 10-inch scope at 187, as seen on my sketch on the
next page. The starlike spot close to the galaxys center 4051
4449
is SN 2009dd, a supernova that was visible at the time. 3938 +44
At the same magnication, NGC 4157 is splendid. The 4138 4013
most prominent part is irregular in brightness and spans

Sk yandTelescope.com May 2016 55

OBSERVING
Deep-Sky Wonders
At 187, the authors 10-inch
reector revealed the some-
what peculiar structure of
NGC 4088 spiral galaxy NGC 4088. The
starlike dot near the galaxys
core is SN 2009dd, a super-
nova that was visible at the
time of observation.

4096 is a lovely sight, showing a mottled face that suggests

the presence of spiral arms unwinding clockwise.
NGC 4096 is some 43 million light-years away. It
belongs to a galaxy group dominated by M106, lodged
next door in Canes Venatici, the Hunting Dogs.
The nal galaxy in our tour is NGC 4051, which oats
1.5 north of the 5th-magnitude star 67 Ursae Majoris.
At 23 my 130-mm refractor discloses only a fairly small,
fuzzy spot with a star at its western edge. At 63 I can tell
NGC 4085
that this spiral galaxy is elongated northwest-southeast.
Upping the power to 91 unveils a small core and starlike
nucleus cloaked in a smoky grey mantle about 2 long
JIM THOMMES

and half as wide. My 10-inch scope at 166 shows a 3

N 1 oval with brighter tips. A gauzy halo spreads mainly
o the ovals northeastern ank, widening the galaxy to
Halton Arp included NGC 4088 in his 1966 Atlas of Peculiar 2. The nucleus remains starlike in a very small, round
Galaxies because one of its arms appears to be partially discon- core. At 213 the core grows brighter toward the center,
nected from the main structure, as shown in this LGRB image. and the asymmetry of the halo is easier to perceive.
The small but conspicuous core of NGC 4051 greets
4096. This spiral galaxy is pretty even at 37 through my our eyes thanks to this Seyfert galaxys active galactic
130-mm scope, with a fairly slim prole thats faint at the nucleus, powered by a black hole weighing in at about
tips and canted north-northeast. At 63 I estimate a tip-to- 1.7 million solar masses. The galaxy is about 47 million
tip length of 5. Its fairly bright for about 4, within which light-years distant and belongs to a group whose bright-
the north-northeastern half is brightest, lending the gal- est member is NGC 4111, another resident of nearby
axy a lopsided look. In my 10-inch reector at 213, NGC Canes Venatici.

Riding the Big Bear

Object Mag(v) Size/Sep RA Dec.

M109 9.8 7.6 4.7 11h 57.6m +53 22

NGC 4102 11.2 2.8 1.2 12h 06.4m +52 43

NGC 4068 12.4 2.5 1.6 12h 04.0m +52 35 NGC 4051
NGC 4088 10.6 5.8 2.2 12h 05.6m +50 32
GEORGE SEITZ / ADAM BLOCK / NOAO / AURA / NSF

NGC 4085 12.4 2.8 0.8 12h 05.4m +50 21

NGC 4157 11.4 8.0 1.1 12h 11.1m +50 29 N

NGC 4096 10.9 5.6 1.4 12h 06.0m +47 29

NGC 4051 is a high-luminosity Seyfert galaxy with an
NGC 4051 10.2 5.2 3.9 12h 03.2m +44 32
active galactic nucleus (AGN). Taken as part of the
Angular sizes and separations are from recent catalogs. Visually, an objects size Overnight Observing Program at Kitt Peak National
is often smaller than the cataloged value and varies according to the aperture and
magnication of the viewing instrument. Right ascension and declination are for Observatory, this image shows NGC 4051s bright AGN
equinox 2000.0. and shhook spiral arms.

56 May 2016 sky & telescope

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 S & T Test Report Dennis di Cicco

Meades 10-inch
LX600-ACF Telescope
The value of the LX600 comes
as much from its timing as
from its advanced technology.
Fork-mounted Schmidt-Cassegrain
telescopes have been around for more than
half a century. Thats a sobering thought for
those of us who vividly remember the rst
advertisements for them appearing in the
pages of this magazine in the 1960s and their
popularity growing almost explosively after
Celestron introduced an attractively priced
8-inch model a few years later. By the early
80s Meade too was building Schmidt-Casseg-
rains, and the familiar silhouettes of stubby-
tube, fork-mounted telescopes were ubiquitous
along the skyline at every star party large and
small. Schmidt-Cassegrains were the telescope
to own whether your interests lay in visual
observing, astrophotography, or both.
Frequent improvements, especially ones
made for astrophotographers, occurred as
Celestron and Meade volleyed design tweaks
back and forth vying for market share, all the
while keeping the telescopes priced within
the reach of many amateurs. Nevertheless,

Meade 10-inch
LX600-ACF Telescope
U.S. price: Telescope & tripod, $4,699;
X-Wedge, $699

While it has the outward appearance of the fork-

mounted Schmidt-Cassegrain telescopes that have
served several generations of amateur astronomers,
ALL PHOTOS BY THE AUTHOR

Meades new LX600-ACF line has state-of-the-art

optics and electronics in a newly engineered telescope
and mount that have been designed for deep-sky
astrophotography. For several months last year the
author tested this 10-inch LX600-ACF from the drive-
way of his suburban-Boston home.

58 May 2016 sky & telescope

as the 20th century drew to a close and digital imag- The LX600 optical-tube assembly (OTA) has an
ing replaced traditional lm-based astrophotography, improved mounting system for the primary mirror
Schmidt-Cassegrains surrendered much of their domi- that virtually eliminates image shift as you focus the
nance to optical designs, albeit expensive ones, better instrument. And theres now a very smooth, dual-speed
able to cover large digital sensors corner to corner with focuser that aids with critical focusing. But achieving
quality star images. precise focus, which is paramount for maximum imag-
Economics played a role, since astrophotographers ing performance, still requires a delicate touch on the
able to aord large-format CCD cameras were also the ne-focus knob, and many astrophotographers will want
ones able to aord expensive telescopes. High-end astro- to use an optional electric focuser (models are available
photography was shifting to an elite group of individuals from Meade and other manufacturers).
who had signicant sums to spend on their hobbies. At Tripod, X-Wedge, and mount. While outwardly
rst blush, it looked like deep-sky astrophotographys similar to other Meade scopes, especially the LX200 line,
love aair with Schmidt-Cassegrains was ending. the LX600 is substantially more robust. Simply put, the
But times change, and now there are moderately 10-inch model I tested is the most stable 10- to 12-inch
priced DSLR cameras that perform exceptionally well fork-mounted scope Ive yet reviewed, with the possible
under the night sky. As such, these cameras are making exception of Meades long-discontinued 12-inch RCX400.
top-notch, long-exposure astrophotography once again And stability is what helps make the LX600 such a suc-
something that falls within the budgets of many ama- cessful imaging platform.
teurs. And thats fueling a market for reasonably priced But theres a price to pay for this weight. The
telescopes that work well for deep-sky photography. complete telescope setup weighs more than 160 pounds
Enter Meades new line of 10- to 16-inch LX600 tele-
scopes. Designed specically for deep-sky imaging, the
LX600 series is everything that the previous generation
of Schmidt-Cassegrain astrophotographers dreamed
about and then some. And after months of testing a
10-inch model that we borrowed from the manufacturer
for this review, I can condently say that its the best tele-
scope of its type that Ive yet tested for astrophotography.

First the Basics

Meade touts revolutionary new technology for its
LX600 scopes, but even the newest technology involved
StarLocks automatic, full-time autoguiding is a
few years old. But thats a good thing, since it means
that its innovation thats already survived the test of
time. What is new, however, is how all this technology is
wrapped in updated hardware designed from the get-go
as a platform for long-exposure astrophotography. Heres
a quick look at the LX600s major features.
Optics. Meade avoids calling the LX600 a Schmidt-
Cassegrain, using instead the acronym ACF for
Advanced Coma-Free optics after a change the company The telescope breaks down
WHAT WE LIKE:
introduced to the traditional Schmidt-Cassegrain optical into four major components:
design more than a decade ago. In addition to being Solid fork mounting designed a 44-pound tripod, the optional
for astrophotography 28-pound X-Wedge (shown
photographically faster than the original f/10 Schmidt-
Cassegrain design (which Meade still oers in its other Automatic full-time autoguiding here attached to the tripod), a
(StarLock) 34-pound base with fork arms,
telescope lines), the f/8 ACF produces nice, round star
images across full-frame DSLR cameras. My review of The Autostar II control systems and a 55-pound optical tube
myriad time-tested features assembly (OTA). Stripping
Meades then-new design, which was introduced under
the OTA of its nder, counter-
the moniker RCX but later changed to ACF, appears WHAT WE DONT LIKE: weights, and StarLock guide
in this magazines February 2006 issue (page 78), and Weight requires two people to scope reduces its weight to
includes side-by-side comparison images made with set up safely 44 pounds, but the author
12-inch versions of the original f/10 and new f/8 optical Documentation possibly confus- still found it dicult to safely
systems. Theres no question that the ACF optics per- ing for beginners assemble the telescope in
form better for deep-sky photography. equatorial mode by himself.

Sk yandTelescope.com May 2016 59

 S&T Test Report

and two handholds on the fork and a single handle on

the back end of the OTA.
To make assembling the scope more manageable,
Meade has designed a nice system for separating the OTA
and fork arms into pieces that, for the 10-inch, weigh 44
and 34 pounds, respectively. This helps, but it still makes
assembly challenging for one person. Indeed, rather than
getting bogged down with details, and despite the fact
that I set the scope up by myself nearly two dozen times,
I will just say that I dont recommend it as a safe process
for one person. Even with the OTA stripped to its mini-
mum conguration (no nder, StarLock guide scope, or
counterweights), I struggled to align the safety catches on
the OTAs declination trunnions with their mating pieces
on the fork tines. It would be easier to do this with the
The heavy-duty X-Wedge gets a thumbs up for its design and scope set up for altazimuth operation, but with the fork
construction. Ball-bearings and large hand knobs on the azi- tilted for astrophotography on the wedge, its an intimidat-
muth and elevation adjustments make easy work of precisely ing operation for one person. The real solution is to have a
moving the heavy telescope during polar alignment.
friend lend a hand when setting up the scope.
Autostar II. The brains for the LX600s GoTo pointing
(including catalogs containing more than 145,000 celestial
objects), tracking, and a host of other advanced features
are in the Autostar II control system, which has been on
Meades high-end scopes for more than a decade. It is a
mature system that works exceptionally well.
Despite its sophistication, Autostar II is relatively
intuitive and easy to operate in the dark with the hand
control. You dont need to keep a printed manual at
hand, since even rarely used features are typically
accompanied by instructions that scroll across the hand
controls 2-line LED display. There are far too many
Autostar II features to write about here, but you can nd
many of the details in the 72-page LX600 instruction
manual, which can be downloaded as a PDF le for free
from Meades website (meade.com).
StarLock. This is really amazing technology, and
it sets the LX600 apart from any other fork-mounted
telescope on the market, bar none. In a nutshell, every
In addition to the scopes 10-inch main aperture and 50-mm
time you slew the LX600 to a new target, StarLock
nder pointing skyward, theres StarLocks 80-mm f/5 guide
automatically acquires a suitable guide star and begins
refractor and a small-aperture, wide-eld camera, which together
perform a variety of important tasks beyond just autoguiding the
guiding the telescope accurately enough for astrophotog-
main telescope for astrophotography. These include precision raphy. There is no need for an external computer or even
centering of celestial objects in the eld of a camera or eyepiece, so much as a button push of input from the user. The
and helping rene the telescopes polar alignment. system is 100% autonomous. And its also non-intrusive,
meaning you can go about using the telescope any
(73 kg), including the 44-pound tripod and optional way you want without interference from StarLock. The
28-pound X-Wedge (a must-have accessory for long-expo- autoguiding begins within about a minute of the scope
sure astrophotography). The OTA and fork mount, with- being moved to a new location (by either GoTo slewing or
out the StarLock guide scope and tube counterweights, the observer pressing the direction buttons on the hand
tips the scales at almost 80 pounds. This makes it about control), and its instantly overridden whenever the scope
30% heavier than Meades corresponding 10-inch LX200 is moved to a new position by any means. A single red
and almost 60% heavier than its 10-inch LX90. With LED on the StarLock guide scope indicates when the sys-
StarLock and counterweights, the assembled scope tem is autoguiding and you can begin shooting pictures.
weighs close to 90 pounds. Furthermore, it is an awk- StarLock also performs a variety of other tasks,
ward scope for one person to set up despite four handles including the precision centering of targets in the eld

60 May 2016 sky & telescope

 As expected, with the
telescope only crudely polar
aligned, an unguided expo-
sure (left) shows signicant
image trailing. But with
StarLock turned on (right), the
tracking was picture perfect.
These back-to-back 5-minute
exposures of the globular star
cluster M13 in Hercules are
with a Nikon D700 camera
and Barlow lens.

of an eyepiece or camera; training the periodic error cor- StarLock performed equally well with the LX600, but
rection (PEC) of the scopes motor drive; and rening the when the frequently turbulent seeing conditions of our
telescopes polar alignment. I detailed StarLocks perfor- New England winters eventually rolled around, StarLock
mance in a review of Meades LX850 German equatorial had a good, but not perfect, track record autoguiding.
telescopes in this magazines December 2013 issue, page To be fair, any autoguider will struggle under crummy
60, so I wont rehash that material here other than to say seeing conditions, so I wasnt surprised to have a few
I remain extremely impressed with the system. guiding failures now and then.
I did, however, encounter a few dierences this time.
Most notably, unlike my previous experience, StarLock The Takeaway
did not autoguide awlessly out of the box. I rst had Overall I was very impressed with the LX600. As some-
to train the PEC and perform what Meade calls an Auto- one who started doing deep-sky photography with an
matic Rate Calibration (ARC). These steps are highly 8-inch Schmidt-Cassegrain in 1972, I can tell you that
automated, involving only a few button presses on the back then the LX600 is what we all dreamed a perfect
hand control and about 15 minutes of time. And since astrophotography setup would be like, except we never
the PEC information is stored in the scopes memory, imagined computers controlling the telescopes pointing
you only need spend a couple of minutes running the and digital eyes doing the guiding!
ARC during subsequent observing sessions. In hind- I can certainly recommend the LX600 for anyone who
sight, it was my experience with the LX850 that was has experience with a fork-mounted Schmidt-Cassegrain
unusual, since Meade clearly states in the LX600 manual telescope, especially one polar-aligned for astropho-
that these steps are an essential procedure to obtain tography. Youll be right at home with the LX600. And
peak tracking accuracy. because Meade still includes accurate setting circles
My original StarLock testing with the LX850 was on the LX600, virtually any method you want to use to
under tranquil summer skies. Under similar conditions polar align the scope will work (something that cant be
said for any of todays scopes that have dispensed with
Left: The Autostar II hand mechanical setting circles).
control operates every feature Id be equally enthusiastic about endorsing the
of the LX600 from GoTo point- LX600 for beginning astrophotographers if the scopes
ing to the advanced functions documentation was a little better. For example, the all-
of StarLock. Below: The LX600
important polar-alignment instructions that are manda-
telescopes can be powered
tory when setting up for astrophotography (the ones that
by a set of eight C batteries
(four housed in each fork arm) scroll across the hand control), while technically correct,
as well as via a conventional are almost physically impossible to do you cant point
12-volt DC input jack on the the OTA to declination 90 and look through the eye-
scopes base. A set of fresh piece while spinning the telescope rapidly on its polar
batteries will last for about axis. My neck hurts just thinking about it. Neverthe-
two nights of observing. less, beginners have surmounted these obstacles in the
past with fork-mounted scopes, and Im sure they will
with the LX600. And when they do, they will be amply
rewarded with a robust astrophotography setup that is
incredibly powerful.

Dennis di Cicco has been writing about equipment in the

pages of Sky & Telescope for more than 40 years.

Sk yandTelescope.com May 2016 61

 New Product Showcase

GUIDESCOPE Orion Telescopes & Binoculars introduces the

60mm Multi-Use Guide Scope with Helical Focuser ($219.99). This
compact 2-inch f/4 guide scope is designed to make autoguiding
deep-sky astrophotos easy and intuitive. The scope includes
heavy-duty tube rings and a 3-inch mounting bar that is compat-
ible with all Orion quick-release nder brackets, and is threaded for
additional mounting options. Its helical focuser has 10-mm of travel
and can accept most autoguiding cameras that connect via a
1-inch nosepiece or a T-thread interface. Six nylon-tipped
thumbscrews allow precise aiming when choosing
guide stars.
Orion Telescopes & Binoculars
89 Hangar Way; Watsonville, CA 95076
800-447-1001; oriontelescopes.com

SK YSAFARI UPDATE One of the most popular planetarium

apps for Apple devices gets a complete makeover. SkySafari 5 (start-
ing at $2.99) changes the look and feel of this popular app, and adds
many new features. SkySafari 5 includes up-to-date ISS and bright
satellite pass notications, expanded object descriptions, and a new
Tonight at a Glance feature with notications of solar system and
bright satellite events. Available in basic, Plus, and Pro versions,
each requires a device running iOS 8 or later, and includes support
for the new Apple Watch. The Plus and Pro versions also incorpo-
rate WiFi Go To telescope control, expanded deep-sky catalogs,
and iCloud synchronization. See the manufacturers website for a
complete listing of features.
Simulation Curriculum (available on the App Store)
11900 Wayzata Blvd., Suite 126, Minnetonka, MN 55305;
1-877-290-8256; simulationcurriculum.com

VIDEO KIT Atik Cameras enters the world of video observing with its Atik
Innity ($1,000). The camera features the highly sensitive and extremely low-noise
Sony ICX825 sensor with a 1,392-by-1,040 array of 6.45-micron pixels to produce
smooth, high-resolution views of deep-sky targets. This USB-2.0 camera can
record up to 3 frames per second at full resolution, which are continually stacked
on your PC computer with the included proprietary control software. The camera
can also operate in 16-bit format and function as an autoguider for your deep-sky
imaging needs with its built-in ST-4 autoguider port. The camera comes complete
with a 3-meter USB-2.0 cable, 1.8-meter cigarette-lighter style power connector,
1-inch nosepiece adapter, and CD with camera drivers and control software.
Atik Cameras
Unit 8 Lodge Farm Barns,
New Rd., Norwich, UK; NR9 3LZ
+44(0)1603-740397; atik-cameras.com

New Product Showcase is a reader service featuring innovative equipment and software of interest to amateur astronomers. The descriptions are based largely on informa-
tion supplied by the manufacturers or distributors. Sky & Telescope assumes no responsibility for the accuracy of vendors statements. For further information contact the
manufacturer or distributor. Announcements should be sent to nps@SkyandTelescope.com. Not all announcements can be listed.

62 May 2016 sky & telescope

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Sk yandTelescope.com May 2016 63

Gary Seronik
Telescope Workshop

Look-Back Time
Reecting on 200+ telescope-making articles.

On september 10, 1998, I walked into the Bay who had previously written an article describing a more
State Road oces of Sky & Telescope for my rst day of rudimentary ex-mirror design. I ended up building two
work as an associate editor. Almost immediately, Roger scopes to test the concept before running Alans article. I
Sinnott handed me two big U.S. Mail totes full of unused cant speak for him, but I was a bit disappointed that the
telescope-making submissions. Welcome to the deep end idea didnt catch on in a big way. Perhaps it was an idea
of the pool, laughed then Editor in Chief Leif Robinson. just ahead of its time.
It was sink-or-swim time. And now, 208 issues later, its One concept that did gain quite a bit of traction,
time to let someone else tread the ATM waters at S&T. though, is telescope thermals. A warm primary mirror is
Ive had the pleasure of showcasing the eorts of arguably the single biggest reason reectors lag behind
many clever equipment makers in this space over the refractors when it comes to rst-rate performance. If
years. And while I dont remember every single article, there were a Nobel Prize for telescope making, Id nomi-
there are a few favorites worth revisiting in this nal nate Bryan Greer for putting this issue front and center.
Telescope Workshop column. I encourage you to give His rst article on the subject, Understanding Thermal
these a second look (or rst look, if youre a new reader). Behavior in Newtonian Reectors (Sept. 2000, p. 125),
Of all the ideas I helped present, I think the most was both carefully researched and compelling. I remem-
innovative was Alan Adlers ex-mirror design (Flex- ber his submission package well it included a video
ing Spheres into High-Quality Telescope Mirrors, Nov. shot using Schlieren imaging to show a telescope mirror
2000, p. 131). The concept was so intriguing that I ew slowly cooling. After seeing that, the problem and its
to Arizona to meet with Alan and fellow ATM Bill Kelly, solution (inexpensive computer fans) were obvious. As a
result of Bryans eorts many more telescopes today
both home-built and commercially produced utilize
fans and deliver better views.
Other innovations were less revolutionary, but no less
helpful. Have you ever wondered where the notion of
collimating with a Barlowed laser came from? You have
Nils Olof-Carlin to thank with his January 2003 article
Collimation with a Barlowed Laser (p. 121) to thank.
I think its genius and so do quite a few readers. The
technique is simple, eective, and can be used to align
a reectors optics in the dark. A couple of manufactur-
ers have even gotten into the act by making commercial
Barlowed-laser collimators. Thanks Nils!
One dominant trend that coincided with my tenure
as the magazines ATM editor was the push for high-
Described in the performance portable scopes. Although the concept
December 2001 doesnt originate with any one telescope maker, it nicely
issue, page 120, this
illustrates the power of iterative design. Albert Highe
8-inch travelscope
and Mel Bartels are two ATMs who have contributed
was one of several
telescopes built by tremendously to the cause of bigger/lighter scopes. All
Gary Seronik and their S&T articles are illuminating.
featured in the pages The ingenuity of telescope makers never fails to
ALAN DYER

of Sky & Telescope. impress me. I remember one article in particular put
that trait to the test. In the March 2009 issue (p. 72), I

64 May 2016 sky & telescope

 FOCUS ON
Sola Fide Observatory Austin, Minnesota
The ASH-DOME pictured is a 126-diameter, electrically oper-
ated unit. The observatory dome shelters a 10-inch, f/10 Dobbins
telescope. The observatory is used for personal observing and by
local amateur astronomy groups year-round.

ASH MANUFACTURING COMPANY

P.O. Box 312, Plainfield, IL, USA 60544
815-436-9403 FAX 815-436-1032
www.ashdome.com
Email: customerservice@ashdome.com
Ash-Dome is recognized internationally by major astronomical groups, amateurs, universities, colleges, and
secondary and primary schools for its performance, durability, and dependability. Manual or electrically operated
units in sizes from 8 to 30 feet in diameter available. Brochures and specifications upon request.
GEORGE BRANDIE

Built for a trip to Australia, Garys Outback

Travelscope was described in his March 2013 Minerva Exo-Planet Search
Telescope Workshop column.

put forth a friendly challenge to readers

to see who could come up with the most
compact 8-inch travelscope. I received a
gratifying number of submissions, and in
the August issue (p. 62) I presented seven
nalists. Their designs revealed two CDK700

characteristics emblematic of telescope

makers in general. First, all seven ATMs
built remarkably elegant, portable scopes. Ascension
200
And yet, no two were alike proving Equatorial
Mount
that there are usually several solutions
to any one problem. Second, the nalists
were scattered far and wide and included
contributors from Canada, Germany,
France, and Holland. Clearly, the enjoy-
ment derived from making and using
telescopes knows no borders.
Sadly, there isnt enough space to Complete
mention every noteworthy contribution
Ive had the good fortune to work on in Observatory Systems
my time here. Id need another 200 issues Corrected Dall Kirkham(CDK)
to do all of them justice! But to everyone and Ritchey-Chrtien (RC) Optics

25th Annual
See us at the
who has added to our shared pool of ATM Ascension 200 Equatorial Mount
knowledge via this department, thank Integrated Observatory Systems
you for the inspiration, generosity, and
imagination youve provided in such great PlaneWave provides complete observatory systems ./24(%!34
abundance. I cant wait to see what youll up to 1-Meter. Completely automated Equatorial !342/./-9
and Alt-Az systems ideal for Universities, &/25-
come up with next! 3UFFERN.9s!PRIL n
institutions or your backyard.

Gary Seronik is an accomplished telescope

maker and observer. He can be contacted
Learn More at www.planewave.com NGC 346 by Colin Eldridge
Taken with CDK700

via his website, garyseronik.com.

 Lunar Imaging

Targeting
Luna
High-resolution close-ups
of the Moon can be a
satisfying challenge for
modest apertures.
Robert Reeves

Lunar photography has always been a relatively simple When attempting to shoot high-resolution crater
procedure: aim your telescope, focus, and snap a bunch of images, youll get more nights of success with a mid-size
pictures. Indeed, the same basic technique used in 1840 telescope compared to a large one. A 6- to 8-inch aperture
by John Draper when he shot the rst lunar daguerreotype will often resolve small lunar features better than larger
remains essentially unchanged for everyday full-disk images instruments in spite of the fact that resolution increases
(see page 52). But taking detailed close-ups of crater elds is with aperture. This is due to seeing cells in the air above
a dierent nut to crack. Recording sharp lunar images used you that are relatively small. A larger telescope will look
to require an enormous amount of eort and luck. through multiple cells of turbulent air while a smaller
Fortunately, with the advent of electronic imaging and scope might look through just one.
frame stacking, that has all changed. These days we use Your choice of camera will also inuence how you can
the established technique of lucky imaging recording achieve a high-resolution image. About a decade ago, most
a series of images in rapid sequence, and then combining video cameras popular with lunar and planetary imagers
the sharpest frames into a nal, high-resolution result. had small CCD detectors with 6-micron pixels, typically in
This permits amateurs with modest equipment to produce a 640 by 480 array. These relative large pixels often required
lunar images that easily surpass the quality of those from additional magnication with a Barlow lens to achieve high-
professional observatories from the age of glass plates and resolution images resolving details of 1 arcsecond or smaller,
lm. Here are some of the methods that can help you get not to mention having to mosaic many images to cover a
the most out of your equipment and take your own sharp substantial area of the lunar surface. Todays planetary cam-
lunar close-ups. eras use fairly large CCD and CMOS arrays with tiny pixels,
often smaller than 3 microns. These little pixels more than
double the resolution over those old webcams, sometimes
eliminating the need for additional magnication boosts
when using telescopes with long focal ratios of f/10 or more.
Additionally, these big detectors allow imaging of much
wider swaths of lunar real estate in one shot.
You can calculate the magnication using this formula:
Arcseconds per pixel = (P/FL) 206.3, where P is the pixel
size in your camera measured in microns, and FL is the
ALL PHOTOS COURTESY OF THE AUTHOR

focal length of your telescope in millimeters.

When choosing a camera for high-resolution lunar
imaging, keep in mind that the Moon is predominantly
a monochrome object, so a color camera is not necessary.
Monochrome cameras are also more sensitive, enabling
you to record at faster frame rates than most color cameras
achieve, particularly at high focal ratios.

ZOOMING IN Facing page: High-resolution shots of crater elds, maria, and rays are within most any amateurs grasp. Author Robert
Reeves shares his techniques to capture sharp images like this one showing Rupes Recta (the Straight Wall). Above: The Moon is loaded
with interesting areas great for any size telescope, such as the oddly elongated crater Schiller found near the southwest limb.

66 May 2016 sky & telescope

Sk yandTelescope.com May 2016 67
 Lunar Imaging

to focus the camera precisely. I use a dual-speed Crayford

focuser with a 10-to-1 reduction, and I clip a clothespin to
the ne-focus knob. This lets me tweak focus by nudging
the clothespin with my ngertip, eliminating the vibra-
tion induced by grasping the knob. Adding a motorized or
electronic focuser is also a good alternative.

Beating the Seeing

No matter what telescope or camera you use to shoot lunar
close-ups, youll be at the mercy of something you have no
control over: Earths turbulent atmosphere. Astronomers
refer to the churning eect of our atmosphere as seeing.
You can use online weather services to get a good idea of
what the sky might be like before you set up. Watch for
the location of the jet stream, a narrow, fast-owing cur-
rent in the upper atmosphere. If the jet stream is passing
MULTI-POINT
overhead in your area, the seeing will be poor.
STACKING A
relatively new pro- While you cant control the atmosphere, you can control
gram for stacking some of the factors that aect local seeing conditions. The
lunar and planetary rst occurs within the telescope itself: allow your optics
images is Auto- to cool to the ambient temperature before beginning to
Stakkert! 2, which shoot. That way you wont be looking through the heat ris-
includes batch- ing o of your primary mirror or objective lens.
processing of mul- The area surrounding your scope is an important
tiple videos and a consideration too. Avoid setting up on concrete or
powerful multi-point asphalt, which slowly radiate heat for much of the night.
alignment routine.
Avoid shooting over buildings and large structures that
emit rising currents of heat at night.
The CMOS and CCD detectors in planetary cameras
are sensitive to ultraviolet and infrared wavelengths.
These come to focus at slightly dierent points than vis-
ible light when passed through refractive optics, reduc-
ing ne detail in your images. So consider installing an
UV/IR lter to block these wavelengths.
Most planetary cameras include an operating pro-
gram and drivers. These generally work well, as long
as they include a few key functions. One of the most
important features is the histogram, which allows you to
monitor the brightness levels in the video output. With-
out a histogram or levels gauge, its dicult to accurately
judge the exposure to avoid overexposing bright areas in
the cameras eld.
I prefer to control my camera using the free program
FireCapture (recapture.de). Written by planetary imager
Torsten Edelmann, this program supports nearly all
planetary cameras and includes many features impor-
tant for lunar, solar, and planet imaging.
Besides your telescope and camera, one additional and
essential accessory for high-resolution lunar photogra-
LUNAR SCOPE You dont need a big telescope to take
phy is a dual-speed focuser. The stock focusers on most
great close-ups of lunar crater elds. Scopes with aper-
telescopes are adequate for prime-focus imaging, but once
tures of 6 to 8 inches will often perform better than larger
you add a Barlow into the mix, you can easily over-shoot scopes in average seeing conditions. The author records
optimum focus with just slight turns. Grabbing the focus most of his lunar images using this Sky-Watcher 180mm
knob at high magnications also introduces furious Maksutov-Cassegrain telescope.
shaking of the eld of view, making it nearly impossible

68 May 2016 sky & telescope

 The altitude of the Moon also greatly aects your length lets you use faster shutter speeds and capture more
images. The lower the Moon is in the sky, the more frames per second, which ensures some sharper frames
atmosphere lies between it and your telescope. So try to are recorded. If the seeing is good, adding a 1.5 Barlow
shoot when the Moon is high up. Another consequence of will resolve more detail. If the seeing is great, even stron-
increased air mass at low elevation is atmospheric disper- ger amplication can be used. In my experience, shooting
sion. The stack of air near the horizon acts like a weak at about f/25 is optimal during the best seeing.
prism, splitting visual light into its separate color wave- Now its time to record some high-resolution videos.
lengths. The higher the Moons altitude, the less disper- While monitoring the histogram, set the cameras gain
sion youll record and the sharper your results will be. at its midpoint and increase the shutter speed until
One way to improve your images in unsteady seeing the right end of the histogram (indicating the bright-
is using lters that transmit only the redder wavelengths est levels in the video) is just short of the right edge of
of the spectrum. Shorter, bluer wavelengths are blurred the graph. Avoid allowing the histogram levels to hit
much more than the longer red and near-infrared wave- the right end of the graph, or else youll end up with
lengths, so a red lter will give you the sharpest results overexposed regions in your stacked images that cant be
in adverse conditions. recovered during processing.
I typically capture many 3,000-frame videos in AVI
Capturing Videos format, which span roughly 30 to 50 seconds, depending
Before you start recording lunar close-ups, make sure on the focal length Ive chosen. This produces 7-gigabyte
your optics are properly aligned collimation is critical video with the Celestron Skyris 236M camera I use. Be
to getting the best results. If you use a Schmidt-Casseg- sure to have plenty of hard-drive space, because youll
rain or Newtonian reector, be sure to check its collima- record upward of 100 GB of videos each night!
tion before imaging. While my Maksutov-Cassegrain is The Moon moves across the sky at a dierent rate
permanently collimated, my C11 occasionally requires than the background stars do, so unless your tracking
slight adjustments despite being permanently mounted. mount includes a lunar rate setting, youll see some
Before hitting Record, spend a few minutes deter- image drift while recording. I keep my videos roughly on
mining what magnication best suits the conditions for target by placing the cursor on a small crater in the eld
the evening. If the seeing is poor, shoot at prime focus and then nudging the drive corrector to keep the crater
without any additional magnication. The shorter focal centered under the cursor.

SUM OF THE PARTS Stacking hun-

dreds of your best video frames results
in a smooth, detailed image ready for
additional processing.

SHARPENING RINGS Right, top: Sharpening can often result in some processing artifacts that need to be corrected. Note the rings seen within
crater shadows in this brightened image of Rupes Recta (the Straight Wall). Right bottom: Shadows in lunar craters should appear black in your
images. If not, you can selectively darken them using the Burn Tool in Adobe Photoshop CC.

Sk yandTelescope.com May 2016 69

 Lunar Imaging

pixels and press the Place AP grid button. This results

in thousands of alignment points. If any points fall in
shadowed regions, increase the Min Bright setting and
click the Place AP grid button again.
Switch back to the control window, and in the Stack
Option column on the right, select the format youd like
your stacked result to have and the number of frames
to stack. I usually stack the best 500 out of 3,000 video
frames. Although the program has a rudimentary sharp-
ening feature, uncheck the Sharpened box if you prefer to
sharpen the results using other software. Finally, initiate
stacking with the 3) Stack button. Once your le has been
REAL OR ARTIFACT? Another artifact to watch out for in stacked into a single image, the result will appear in a new
lunar close-ups is false central peaks in small craters. These folder within the original location of your video les.
often appear in images taken in poor seeing conditions. At this stage, you can move your image into another
image-processing program to sharpen the details. If you
Stacking and Sharpening use RegiStaxs wavelet sharpening, experiment with
Now that you have some quality videos, its time to sort the slider settings; no two optical systems are the same,
and stack the best frames into single images. This can be and what works for one scope-and-camera combination
performed using a host of programs, but I prefer using might be too much for another. The key to great high-
AutoStakkert! 2 (autostakkert.com) to stack my videos, and resolution lunar images is to avoid over-sharpening.
RegiStax (www.astronomie.be/registax) or Adobe Photo- My favorite sharpening tool in AdobePhotoshop CC
shop CC (adobe.com) to sharpen and clean up the results. is the new Shake Reduction lter, located at Filter >
AutoStakkert! 2 is an easy-to-use program that lets Sharpen > Shake Reduction. The lter includes artifact
you process many videos in a single batch. To use the suppression and noise reduction, which produce results
program, begin by clicking 1) Open and select your rst similar to shooting through better seeing or using a
video. Next, under the Image Stabilization tab, select higher-resolution instrument.
Surface, and check the Improved Tracking box. Now As with most astrophotos, some additional process-
click the 2) Analyse button, and the program will evalu- ing is helpful beyond sharpening. I prefer to do any nal
ate your video. Once its complete, switch to the screen processing in Photoshop CC.
showing your video, and on the left-hand column, select Stacking several hundred frames eectively increases
an alignment point (AP) size I usually choose 25 the bit depth of the nal result, so AutoStakkert! 2
generates 16-bit TIF, PNG, or FIT images with a very
high signal-to-noise ratio. This makes it easy to brighten
dark areas without increasing objectionable noise in
shadowed regions close to the terminator. I often do this
using the Camera Raw lter (Filter > Camera Raw).
Finally, I perform any cosmetic cleanup. An unin-
tentional side eect of the stacking and sharpening
processes is they can generate artifacts that mimic real
detail. Recognizing and removing them greatly improves
your nal result. Using the Burn Tool from the tool pal-
ette set to about 5% is the easiest way to darken shadow
areas, as well as reduce any ring artifacts along the edge
of craters. Use the Eraser or Clone Stamp tools to remove
false central peaks in smaller craters, being careful not
to eliminate real detail or duplicate an existing feature.
By following these tips, exquisitely detailed images
of crater elds on the Moon will be within your grasp.
SUNSET TERMINATOR Using these tips, you can
Relive the most exciting times in space exploration with
capture your own high-resolution images of craters like
your own telescope and rediscover the joys of lunar pho-
the above picture of craters Gutenberg (top) through
Gaudibert (lower left). This image was recorded with the
tography by exploring our neighboring world.
Sky-Watcher 180mm Maksutov (seen on page 68) with a
Celestron Skyris 236M CMOS camera. Robert Reeves shoots the Moon at every opportunity from his
backyard observatory in San Antonio, Texas.

70 May 2016 sky & telescope

 35th Annual
SAS Conference
Promoting Amateur
Science and
Amateur-Professional
Collaboration

TAKAHASHI

June 16-18
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INTRODUCING THE NEW

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 RT-Version www.alpineastro.com

NT-Version Diamonds are a mans best friend SC-Version

when they drive a high precision focuser.
Take a Baader Diamond Steeltrack and be happy ever after.

48 th Annual

Sell Your Used Equipment

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72 May 2016 sky & telescope

 J. Kelly Beatty
Gallery
Gallery showcases the nest astronomical images submitted to us by our readers. Send your best shots to
gallery@SkyandTelescope.com. See SkyandTelescope.com/aboutsky/guidelines.

PL ANET PARADE
Gradient Lok
As seen before dawn on
January 29, 2016, from
Kuala Lumpur, Malaysia,
the widely viewed arc of all
ve naked-eye planets
plus the Moon passed
almost directly overhead.
Details: Canon EOS 6D
DSLR camera used at ISO
800 and an 8-to-15-mm
zoom lens used at 14 mm.
Exposure: 5 seconds.

Jupiter

Mars

Saturn

Venus
Mercury

Sk yandTelescope.com May 2016 73

 Gallery

SUN-AND -MOON DJ VU
Marcella Giulia Pace & Marco Meniero
The coincidence of a lunar eclipse at an equinox permitted this
dramatic pairing of moonrise on September 27, 2016, and sun-
rise the previous morning with the same tree-lined horizon.
Details: Canon PowerShot SX50 HS camera; Moon: 1/1 2 5 -second
exposure at ISO 100; Sun: 5 -second exposure (ltered) at ISO 80.

74 May 2016 sky & telescope

SWAYING THROUGH CEPHEUS
David Mittelman
The Elephants Trunk (vdB 142) winds for some 20 light-years
through the star-forming complex IC 1396. Its rim glows due to
light from the very bright, massive star HD 206267 (not seen).
Details: PlaneWave CDK20 astrograph and FLI MicroLine ML16803
CCD camera with Astrodon lters. Total exposure: 27 hours.

Sk yandTelescope.com May 2016 75

 Gallery

PAIRED POLLY WOGS

John Vermette
The emission nebula IC410, located about 12,000 light-
years away in Auriga, provides the backdrop for a pair
of isolated, backlit clouds called the Tadpoles.
Details: Hyperion 12.5-inch astrograph and SBIG STL-
11000M CCD camera with H and RGB lters. Total
exposure: 9 hours.

SUNFLOWER
Leo Aerts
As active region 12132 crossed the Suns face on
August 5, 2014, its main sunspot group took on the
appearance of a Van Gogh-like sunower roughly
1 arcminute across.
Details: Celestron C14 Schmidt-Cassegrain telescope,
Baader solar lter, and Imaging Source DMK31AU03.AS V
Visit SkyandTelescope.com/gallery
CCD video camera. Stack of 800 0 -second exposures. ffor more of our readers astrophotos.

76 May 2016 sky & telescope

 Introducing a Hold the Solar System
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 TELESCOPES CLASSIFIEDS

UNIQUE TELESCOPE: Theres not seeing. Property oered at $489,500.

another like it for sale in the world. Contact realtor Randy Everett: (575)
Beautiful 12-inch f/12.2 D&G refrac- 682-2583, everett.team@gmail.com
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www.darksky.org pier and C-14. Enjoy 1 arc second of third month before publication date.

Sk yandTelescope.com May 2016 81

 Inside This Issue
Specialty astronomy equipment dealers and manufacturers are an important resource for amateur and professional
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82 May 2016 sky & telescope

 Index to Advertisers

Alpine Astronomical, LLC. . . . . . . . . . . . 72 Obsession Telescopes. . . . . . . . . . . . . . . 63

Artemis CCD Ltd. . . . . . . . . . . . . . . . . . . .15 Oceanside Photo & Telescope . . . . . . . . 63

Ash Manufacturing Co., Inc.. . . . . . . . . . 65 Optic Wave Laboratories. . . . . . . . . . . . . 80

SkyandTelescope.com
800-253-0245
Astro Haven Enterprises . . . . . . . . . . . . . 80 Orion Telescopes & Binoculars . . . . . . . .13
IN THE NEXT ISSUE
Astro Optik Kohler. . . . . . . . . . . . . . . . . . 79 Peterson Engineering Corp. . . . . . . . . . . 79

Astronomics . . . . . . . . . . . . . . . . . . . . . . 80 PlaneWave Instruments . . . . . . . . . . . . . 65

Astro-Physics, Inc. . . . . . . . . . . . . . . . . . . 80 PreciseParts . . . . . . . . . . . . . . . . . . . . . . 78

DiscMounts, Inc. . . . . . . . . . . . . . . . . . . 79 Princeton University Press . . . . . . . . . . . 63

Durango Skies . . . . . . . . . . . . . . . . . . . . . 80 Prism America, Inc. . . . . . . . . . . . . . . . . 57

Farpoint Astronomical Research . . . . . . 78 Revolution Imager . . . . . . . . . . . . . . . . . 79

Finger Lakes Instrumentation, LLC . . . . . 1 RTMC Astronomy Expo . . . . . . . . . . . . . 72

Foster Systems, LLC . . . . . . . . . . . . . . . . 78 Shelyak Instruments . . . . . . . . . . . . . . . . 78

After the Explosion
Learn how to observe one of the most
challenging deep-sky targets, the
Glatter Instruments . . . . . . . . . . . . . . . . 78 Sky & Telescope. . . . . . . . . . . . . . . .71, 72, 77
on-the-move remnants of Tychos
Supernova (above).
Goto USA, Inc. . . . . . . . . . . . . . . . . . . . . . 5 Sky-Watcher USA . . . . . . . . . . . . . . . . . . . 9
Is Red Light Best?
International Dark-Sky Association . . . . 81 Society for Astronomical Sciences . . . . . 71 Skygazers often use red light to
protect their night vision, but is red
iOptron . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Software Bisque. . . . . . . . . . . . . . . . Cover 3 really the ideal color?

Kasai Trading Co., Ltd. . . . . . . . . . . . . . . 79 Stellarvue . . . . . . . . . . . . . . . . . . . . . . . . . 81 The Nebula Wars

More than a century ago, it deed
Kitt Peak National Observatory . . . . . . . 71 Technical Innovations . . . . . . . . . . . . 79, 80 belief that small scopes could image
big nebulae best.
Knightware. . . . . . . . . . . . . . . . . . . . . . . . 80 Tele Vue Optics, Inc. . . . . . . . . . . . . Cover 2
Skygazing Safari
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Lunatico Astronomia . . . . . . . . . . . . . . . 78 TelescopeAdapters.com . . . . . . . . . . . . . 78
this observing adventure in the heart
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Mathis Instruments . . . . . . . . . . . . . . . . 79 Texas Nautical Repair, Inc. . . . . . . . . . . . 71
Sky-Watcher AZ-EQ5 Mount
NASA / CXC / RUTGERS / J.WARREN & J.HUGHES ET AL.

Meade Instruments Corp.. . . . . . 3, Cover 4 The Teaching Company . . . . . . . . . . . . . 37 We test this versatile Go To mount
in equatorial and alt-azimuth
Medomak Camp . . . . . . . . . . . . . . . . . . . 81 TravelQuest . . . . . . . . . . . . . . . . . . . . . . . 57 congurations.

NexDome. . . . . . . . . . . . . . . . . . . . . . . . . 80 Willmann-Bell, Inc. . . . . . . . . . . . . . . . . . 79 On newsstands April 26th!

Northeast Astronomy Forum . . . . . . . . . .17 Woodland Hills Telescopes . . . . . . . . . . 17 Find us on
Facebook & Twitter
Observa-Dome Laboratories . . . . . . . . . 57

Sk yandTelescope.com May 2016 83

 Focal Point Greg Bryant

Highway to Heaven
Traveling for astronomy can bestow uncommon, and unforeseen, benets.

For many of us, observing the night p. 84). Scanning the western sky with my table sight: Hyakutake, the Great Comet
sky provides a relaxing break from the 6-inch f/5 Vixen reector, I came across a of 1996, with its tail like an exclamation
intensity of daily life. Its also a journey: white, triangular nebulosity. A cry from mark dividing the sky. The following year
exploring the rmament with our eyes another amateur nearby that hed located I drove Bill Bradeld, the 20th centurys
and broadening our horizons mentally. Halley drew me momentarily from my greatest visual comet hunter, to a star
But an actual journey can add telescope to his. Thats when I realized Id party where we viewed Comet Hale-Bopp
adventure to stargazing and oer other already swept up the comet myself. shining brightly.
dividends not available in our backyards. In March 1986, we made an eight-hour Occasional strokes of fortune have
Locating a nearby site for better viewing, round trip to see Halley rising in the favored me when Ive hit the road for
heading farther to a dark-sky location for predawn sky from a friends farm. My astronomy. My wife, an astrophysicist,
the occasional getaway from light pol- nal view of Halley with the unaided eye is a regular observer with the 3.9-meter
lution, or planning a vacation or special involved leaving town again, on April 24, Anglo-Australian Telescope at Siding
expedition to behold a celestial event 1986. Normally, one wouldnt undertake Spring Observatory. In 2011, I was there
all can confer unique rewards. a three-hour drive to observe under a full with her and our two sons, then aged
A trek away from home can be just the Moon. But this was something extraordi- 10 and 8. We were staying in the Direc-
thing to experience sights youve never nary a total lunar eclipse was taking tors Cottage, and Id just come in from
seen and maybe refresh and invigorate place and my family gazed one last stargazing for a coee. The phone rang.
your hobby. Some of my own most time upon the famous comet high over- It was Robert McNaught calling: Greg,
memorable moments in astronomy have head, together with the eclipsed moon. I think Ive found a comet. My sons and
come about as a result of traveling. Comets have been a reason for head- I walked to the 0.5-m Uppsala Southern
In 1985, when I was 15, my family ing far aeld at other times as well. Schmidt Telescope where Robert was
drove me to a dark-sky observatory for my During an early-morning jaunt to the working, and we became the second,
rst look at Comet Halley (S&T: Feb. 1999, mountains, I witnessed an unforget- third, and fourth people in the world to
see what would subsequently be called
Comet C/2011 N2 (McNaught).
Getting far from home has also
enabled me to see Supernova 1987A
under dark skies, delight in a spectacular
Leonid meteor shower in 2001, and stand
in awe of a perfect solar eclipse at Cairns
in 2012.
All this notwithstanding, on the
afternoon of July 22, 2028, I expect to be
sitting right in my own backyard. Why?
A total solar eclipse will cross Australia
that day, and my home city of Sydney
lies right in its path. Mind you, if the
weather forecast that day is looking better
elsewhere.
JOHN S. DYKES

Contributing Editor Greg Bryant served as

editor in chief of Australian Sky & Tele-
scope from 2006 to 2014.

84 May 2016 sky & telescope

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