Physics Open Course

JOY OF STAR WATCHING

BOOKS FOR STUDY : 1. The Great Universe- G.K.Sasidharan- S.Chand


2. Joy of star watching – BimanBasu- National Book Trust , India.

REFERENCE : Jyothishavum Jyothisasthravum- K. Pappootty- K.S.S.P.
Cunningham

Open(Physics) Course -Theory

5D01PHY: B. Joy of star watching

Semester-V, Credit-2, Contact hours -36, Max. Ext. Marks- 20,Max. Int. marks-5

Module 1: Astrophysics

The study of the Universe - Problems and prospects. The Universe - its origin-
_Galaxies__Milkyway. A star is born. The death of a star. The comets–The pole star
(Book 1) (14 Hrs)(Marks: Minimum 7)
Module 2: The constellations

Orion- Canis major-Taurus—Leo-(Book 2) (2 Hrs)

(Marks: Minimum 2 )

Module 3: Stars in kerala culture

The origin and expansion of Astrology -Stars and constellations in Kerala culture- (12 Hrs)
(Marks: Minimum 6)
Module 4: Star watching

How to experience star watching — For a better view (Book 2) (8 Hrs) (Marks: Minimum: 5)

Book for study:

1. The Great Universe- G.K.Sasidharan- S.Chand

2. Joy of star watching – BimanBasu- National Book Trust , India.

Book for reference:

1.Jyothishavum Jyothisasthravum- K. Pappootty-K.S.S.P.

Origin of the Universe

Why are we here ?

Where did we come from ?

What did we know about the universe and when did we know it ?
Central Africa in the area that is now known as Democratic Republic of the Congo
 you are here > Famous Astronomers

Great Astronomers

Thales (624-547 B.C., Ionian) was a Greek

philosopher who traveled widely in Mesopotamia
and Egypt, and brought astronomical records
from these cultures back to Greece. He believed
that the Earth is a disk floating on an endless
ocean. Legend has it that he correctly predicted a
solar eclipse in the year 585 B.C.

Anaximander (611-547 B.C., Ionian) was a Greek

philosopher who made the first detailed maps of
the Earth and the sky. He knew that the Earth
was round, and believed that it was free-floating
and unsupported. He measured its
and Egypt, and brought astronomical records
from these cultures back to Greece. He believed
that the Earth is a disk floating on an endless
ocean. Legend has it that he correctly predicted a
solar eclipse in the year 585 B.C.

Anaximander (611-547 B.C., Ionian) was a Greek

philosopher who made the first detailed maps of
the Earth and the sky. He knew that the Earth
was round, and believed that it was free-floating
and unsupported. He measured its
circumference, and was the first to put forward
the idea that celestial bodies make full circles in
their orbits. One of his greatest contributions was
the fact that he was the first to conceptualize
space as having depth.

Pythagoras (569-475 B.C., Ionian) was a

mathematician who put forward the idea that the
universe is made of crystal spheres that encircle
circumference, and was the first to put forward
the idea that celestial bodies make full circles in
their orbits. One of his greatest contributions was
the fact that he was the first to conceptualize
space as having depth.

Pythagoras (569-475 B.C., Ionian) was a

mathematician who put forward the idea that the
universe is made of crystal spheres that encircle
the Earth. According to him, the Sun, the Moon,
the planets, and the stars travel in separate
spheres. When the spheres touch each other, a
'music of the spheres' can be heard.

Aristotle (384-322 B.C., Greek), the great

philosopher, proved that the Earth is spherical,
and believed that it was at the center of the
universe. His reason for believing this was
actually quite scientific: he knew that if the Earth
revolved around the Sun, then we should see the
the Earth. According to him, the Sun, the Moon,
the planets, and the stars travel in separate
spheres. When the spheres touch each other, a
'music of the spheres' can be heard.

Aristotle (384-322 B.C., Greek), the great

philosopher, proved that the Earth is spherical,
and believed that it was at the center of the
universe. His reason for believing this was
actually quite scientific: he knew that if the Earth
revolved around the Sun, then we should see the
stars shift position throughout the year. Since he
did not have the technology to detect this shift, as
we do today, he concluded that Earth must rest at
the center of the universe. According to him, the
Sun, planets, and stars were located in spheres
that revolved around the Earth.
Aristarchus (310-230 B.C., Greek) was the first to
did not have the technology to detect this shift, as
we do today, he concluded that Earth must rest at
the center of the universe. According to him, the
Sun, planets, and stars were located in spheres
that revolved around the Earth.
Aristarchus (310-230 B.C., Greek) was the first to
put forward the idea that the Sun was actually in
the center of the universe. His theory was
considered far too radical. Unfortunately, history
tends to forget that he came to this conclusion
about 1,750 years before Copernicus did! He also
attempted to measure the relative distances
between the Earth and the Sun and the Earth and
the Moon. Even though he used a reasonable
method, his results were not very accurate,
because he lacked the technological equipment
to make a precise measurement.
Hipparchus (190-120 B.C., Greek) is widely
considered to be the greatest astronomer of
ancient times. He compiled the first known star
catalog to organize astronomical objects, and
also came up with a scale to define the
between the Earth and the Sun and the Earth and
the Moon. Even though he used a reasonable
method, his results were not very accurate,
because he lacked the technological equipment
to make a precise measurement.
Hipparchus (190-120 B.C., Greek) is widely
considered to be the greatest astronomer of
ancient times. He compiled the first known star
catalog to organize astronomical objects, and
also came up with a scale to define the
brightnesses of stars. A version of this magnitude
system is still used today. He measured the
distance from the Earth to the Moon to be 29.5
Earth diameters (we know today that the real
value is 30 Earth diameters). Perhaps his
greatest discovery was the precession, or
wobble, of the Earth's axis, which is caused by
the gravitational pull of the Sun and Moon.
Claudius Ptolemy (85-165 A.D., Greek) was an
astronomer who used Hipparchus' extensive
observations to develop a model that predicted
the movements of the Sun, Moon, planets, and
stars. His model, called the Ptolemaic system,
Earth diameters (we know today that the real
value is 30 Earth diameters). Perhaps his
greatest discovery was the precession, or
wobble, of the Earth's axis, which is caused by
the gravitational pull of the Sun and Moon.
Claudius Ptolemy (85-165 A.D., Greek) was an
astronomer who used Hipparchus' extensive
observations to develop a model that predicted
the movements of the Sun, Moon, planets, and
stars. His model, called the Ptolemaic system,
visualized an Earth-centered universe and
assumed that all astronomical objects move at
constant speeds in circular orbits. The circle was
considered by the ancients to be the perfect
shape, and regardless of the evidence against
circular orbits, Ptolemy built his model to fit this
idea. The Ptolemaic model is one of the longest
upheld scientific theories in history: it was the
cornerstone of astronomy for 1,500 years.
al-Khwarizmi (780-850, Islamic) was the inventor
of algebra. He developed this mathematical
device completely in words, not mathematical
expressions, but based the system on the Indian
accurate than the Julian and came close to the
Gregorian. An amazing feat was his calculation of
the year to be 365.24219858156 days long,
which is accurate to the sixth decimal place!

Nicolaus Copernicus (1473-1543, Polish) began a

new era of astronomy when he concluded that
the Sun was the center of the universe instead of
the Earth. Copernicus felt that the Ptolemaic
system was contrived, but in his revisions of that
model, he kept the orbits circular. The
revolutionary idea was not popular with the
Church, but several other astronomers such as
Brahe and Galileo helped to eventually prove that
this model of the universe more accurately
portrayed reality.
Tycho Brahe (1546-1601, Danish) built an
observatory from which he made the most
accurate astronomical observations up to that
time. His observatory contained sophisticated
equipment for mapping star positions, and for
orbit the Sun and the Sun orbits the Earth.
Galileo Galilei (1564-1642, Italian) is the father of
observational astronomy. In 1609, he heard about
the Dutch invention of the telescope, and built
one for himself. Even though his telescope was
not very powerful compared to the amateur
equipment available today, he was able to make
a number of stunning discoveries which changed
the face of astronomy. He saw the craters,
mountains, and valleys of the Moon, noticed the
huge number of stars making up the Milky Way,
kept precise records of sunspot activity and the
phases of Venus, and discovered four moons
orbiting Jupiter. These moons are still called the
Galilean Moons today, in honor of the earth-
shattering scientific effects of the discovery.
During a time when the Earth was still considered
to be at the center of the universe, he publicized
the fact that other astronomical bodies, such as
Jupiter's moons, were clearly revolving around
something other than the Earth. Galileo's support
of the Copernican model of the universe
frightened the Church, which put Galileo on trial
in 1633. He was forced to renounce his
Copernican views and was held under house
arrest for the rest of his life.
Johannes Kepler (1571-1630, German) was
Copernican views and was held under house
arrest for the rest of his life.
Johannes Kepler (1571-1630, German) was
Tycho Brahe's assistant and student. He inherited
his teacher's extensive collection of astronomical
records, and used them to develop three laws of
planetary motion. He believed in the Copernican
model of the universe, although he found it
difficult to fit Tycho's observations of Mars into the
model with a circular orbit. He therefore used the
idea of elliptical orbits to describe the motions of
the planets, which became known as Kepler's
first law. His second law states that a line from
the Sun to a planet sweeps out equal areas in
equal amounts of time. The third law was a
masterpiece of simplicity: the square of the
number of years of a planet's orbital period is
equal to the cube of that planet's average
distance from the Sun.
equal amounts of time. The third law was a
masterpiece of simplicity: the square of the
number of years of a planet's orbital period is
equal to the cube of that planet's average
distance from the Sun.

Giovanni Cassini (1625-1712, Italian) was the

astronomer who first discovered the division in
the rings of Saturn, today known as the Cassini
division. He also found four moons orbiting
Saturn, and measured the periods of rotation of
Mars and Jupiter. The Cassini space mission
currently on its way to Saturn was named after
him.

Isaac Newton (1643-1727, British) was a

mathematician who developed extensive
mathematics to describe the astronomical models
of Copernicus and Kepler. His Theory of
Universal Gravitation was the foundation of
Mars and Jupiter. The Cassini space mission
currently on its way to Saturn was named after
him.

Isaac Newton (1643-1727, British) was a

mathematician who developed extensive
mathematics to describe the astronomical models
of Copernicus and Kepler. His Theory of
Universal Gravitation was the foundation of
Kepler's laws of planetary motion, but it also went
further: Newton showed that the laws governing
astronomical bodies were the same laws
governing motion on the surface of the Earth.
Newton's scientific ideas are so complete that
they still offer an accurate description of physics
today, except for certain cases in which 20th
century physics must be used.

Edmond Halley (1656-1742, British) became

placed on the H-R diagram.

Albert Einstein (1879-1955, German) was

probably the greatest mind of the twentieth
century. His Special Theory of Relativity,
proposed in 1905, extended Newtonian
Mechanics to very large speeds close to the
speed of light. It describes the changes in
measurements of physical phenomena when
viewed by observers who are in motion relative to
the phenomena. In 1915, Einstein extended this
further in the General Theory of Relativity, which
includes the effects of gravitation. According to
this theory, mass and energy determine the
geometry of spacetime, and curvatures of
spacetime manifest themselves in gravitational
forces.

Arthur Eddington (1882-1944, British) proved

Alexander Friedmann (June 16, 1888 – September 16, 1925)
was a Russian and Soviet physicist and mathematician.
He is best known for his pioneering theory that the universe was expanding,
governed by a set of equations he developed now known as the
Friedmann equations.
Georges Lemaître, (17 July 1894 – 20 June 1966)
was a Belgian Catholic priest, astronomer and professor of physics
at the Catholic University of Leuven. He proposed on theoretical
grounds that the universe is expanding, which was observationally
confirmed soon afterwards by Edwin Hubble.He was the first to derive
what is now known as Hubble's law and made the first estimation of
what is now called the Hubble constant, which he published in 1927,
two years before Hubble's article. Lemaître also proposed what
became known as the "Big Bang theory" of the origin of the universe,
which he called his "hypothesis of the primeval atom" or the "Cosmic Egg
George Gamow (March 4, 1904- August 19, 1968),
was a Russian-American theoretical physicist and cosmologist.
He was an early advocate and developer of Lemaître's
Big Bang theory.
 Edwin Powell Hubble (November 20, 1889 – September 28, 1953)
was an American astronomer. He played a crucial role in establishing
the fields of extragalactic astronomy and observational cosmology
and is regarded as one of the most important astronomers of all time.
Hubble discovered that many objects previously thought to be clouds
of dust and gas and classified as "nebulae" were actually galaxies
beyond the Milky Way.

The 100-inch Hooker telescope at Mount Wilson Observatory that Hubble used to
measure galaxy distances and a value for the rate of expansion of the universe.
Sir Fred Hoyle (24 June 1915 – 20 August 2001)
was a British astronomer who formulated the theory of
stellar nucleosynthesis. He also held controversial stances
on his rejection of the "Big Bang" theory
Arno Allan Penzias (26 April 1933) is an American physicist, radio astronomer and Nobel laureate in
physics who is co-discoverer of the cosmic microwave background radiation along with Robert Woodrow
Wilson, which helped establish the Big Bang theory of cosmology.
Bigbang Theory

13.772 billion years

old Universe !!!
The universe had a definite beginning.

The ‘best’ explanation for the existence of the universe is currently

the Big Bang Theory.

The Big Bang is thought to be an explosion from a SINGULARITY

(a single point of density – where all known space was compressed)

This happened 13.8 bn years ago

They don’t really know what the singularity was or ‘how long’ it had been there.
 Evidence Supporting the Big Bang Theory

Hubble’s Law: the speed of the galaxies moving away from each other causes a change in
the light spectrum, ‘red shift’.

Background radiation: We can still detect radiation from an explosion of this size – the radiation is
the same everywhere on earth (TV static, etc).

Composition of Older Galaxies: Analysis of light from galaxies towards the ‘outside’ of the universe
confirm theories about the early universe. They are made up of approx 93% H, 7% He.
 Stellar Evolution
H R Diagram (Hertzsprung-Russell Diagram)
 Main sequence stars
Active Shell of hot gas with shrieked
and exposed core
i on Core continues to shrink
ct
n tra
c o ion
n al act
a tio n re
v it sio
a Fu
Gr Fuel begins to run out
core shrinks
Mass < 8 Ms
He —> C
Mass > 1.4 Ms (Chandrasekhar limit)
Outer layer puff out —> cooling

Cloud of cold gas +Tiny grained dust - Nebula

Gravitational contraction - T increases
PROTOSTARS s
M
15
s <
a s
m
Mass > 8 Ms o re
C
Co
re
m as
s>
Rapid H fusion and at the end 15
M s
Fe nuclei are formed.
Fe nuclei absorb energy
100 times diameter of sun
Core collapse
Explodes into brilliant burst of light
 The Comets

looks like a dust tail

A comet is an icy body that releases gas or dust. Comets contain dust, ice, carbon dioxide,
ammonia, methane and more. Astronomers think comets are leftovers from the gas, dust,
ice and rocks that initially formed the solar system about 4.6 billion years ago.Some researchers
think comets might have originally brought some of the water and organic molecules to Earth
that now make up life here. To research this hypothesis, the Rosetta mission, which landed a
probe on a comet on Nov. 12, 2014, is studying its nucleus and environment, observing how
it changes as it approaches the sun. Comets orbit the sun, but most are believed to inhabit in
an area known as the Oort Cloud, far beyond the orbit of Pluto. Occasionally a comet streaks
through the inner solar system; some do so regularly, some only once every few centuries.

Halley's Comet is likely the most famous comet in the world. It becomes visible to the naked
eye every 76 years when it nears the sun. When Halley's Comet zoomed near Earth in 1986,
five spacecraft flew past it and gathered unprecedented details, coming close enough to study
its nucleus. The comet Shoemaker-Levy 9 collided spectacularly with Jupiter in 1994, with the
giant planet's gravitational pull ripping the comet apart for at least 21 visible impacts. The largest
collision created a fireball that rose about 1,800 miles (3,000 km) above the Jovian cloud tops
as well as a giant dark spot more than 7,460 miles (12,000 km) across - about the size of the Earth.

A recent, highly visible comet was Hale-Bopp, which came within 122 million miles (197 million km)
of Earth in 1997. Its unusually large nucleus gave off a great deal of dust and gas — estimated at
roughly 18 to 25 miles (30 to 40 km) across — appeared bright to the naked eye.

Comet ISON was expected to give a spectacular show in 2013. However, the sun-grazer did
not survive its close encounter with the sun and was destroyed in December.
 The Pole Stars
A pole star is a visible star, preferably a prominent one, that is approximately aligned
with the Earth's axis of rotation; that is, a star whose apparent position is close to one
of the celestial poles, and which lies approximately directly overhead when viewed from
the Earth's North Pole or South Pole.

Polaris is the North Pole Star

Sigma Octantis, which is sometimes called the South Star.

 The Constellations

88 constellations are there

Zodiac constellations are constellations that lie along the plane of the ecliptic

The 12 constellations in the zodiac family can all be seen along the ecliptic.

Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius and Pisces.
Nakshatra Names and Their Meanings

The name of nakshatras in Malayalam, Tamil, Telugu and Hindi along with their
meanings is given below.
Hasta അtം அsதm !"# हस्त
The hand
Nakshatra Malayalam Tamil Telugu Hindi
Chitra ചിtിര Bt,ைர $%# िचत्रा
Ashwini അശ#തി அs#$ The bright!"#$
one अिश्वनी
Horse like woman
Swati േചാതി Cவா, &'( स्वाती
Sword or Independence
Bharani ഭരണി பர' %&' भरणी
The bearer Vishaka വിശാഖം #சாகm )*+ िवशाखा
Forked (having branches)
Krittika കാർtിക காrt,ைக ()*+( कृित्तका
The Cutter Anuradha അനിഴം அDஷm ,-./ अनुराधा
Disciple of divine spark
Rohini േരാഹിണി ேரா/' ,-' रोिहणी
Red faced One Jyeshta തൃേkA ேகFைட 0123 ज्येष्ठा
The eldest
Mrigashirsha മകയിരം 01க23டm .)/"& म्रृगशीषार्
Moola മൂലം Gலm 45 मूल
the deer's head The root

Ardra തിരുവാതിര ,1வா,ைர 0&12

Purva Ashadha आद्रा പൂരാടം 9ராடm 6.'78 पूवार्षाढा
Moist One Previous invincible one

Punarvasu പുണർതം 34&#5

7னr9சm Uttara Ashada पुनवर्सഉ:താടം
ु உt,ராடm 9%#.78 उत्तराषाढा
Restoring goods Latter invincible one

Pushya പൂയം 9சm Shravana 63789 पुष्य തിരുേവാണം ,1ேவாணm *

: ;< श्रवण
The audible
Nourishing
Dhanistha അവിAം அ#Fடm /=2> धिनष्ठा
Ashlesha ആയില8ം ஆ<lயm 0:;7 आश्लेषा
The richest one
The embracer
Shatabhisaa ചതയം சதயm ?%@2 शतिभषक्
Magha മകം மகm <=
Hundred healers मघा
The wealthy one
Purva Bhadrapada പൂരുരുAാതി 9ரFடா, 6.'AB: पूवर्भाद्रपदा
Purva Phalguni പൂരം 9ரm >&# feet
Former blessed ?@A $ पूवर् फाल्गुनी
Earlier reddish one
Uttara Bhadrapada ഉ:തAാതി உt,ரFடா, 9%#.AB: उत्तरभाद्रपदा
Uttara Phalguni ഉ:തം உt,ரm Latter blessed
BC+&feet
?@ A $ उत्तर फाल्गुनी
Latter reddish one Revati േരവതി ேரவ, C;( रेवती
The wealthy

Advertisement
 Orion Constellation

Lies on the celestial equator.

Also known as the Hunter, as it is associated with one in Greek mythology.

It represents the mythical hunter Orion.

 Canis Major Constellation

Canis Major is a constellation in the southern celestial hemisphere.

Canis Major contains Sirius, the brightest star in the night sky, known as the "dog star".
 Taurus (constellation)
Taurus is one of the constellations of the zodiac.
Taurus is a large and prominent constellation in the northern hemisphere's winter sky.
 Leo (constellation)
Leo is one of the constellations of the zodiac, lying between Cancer to the west and Virgo to the east.
Its name is Latin for lion.