11

Physical Science
Quarter 4 – Module 1
Astronomy Before the Advent of
the Telescope
Physical Science – Grade 11
Quarter 4 – Module 1: Astronomy Before the Advent of the Telescope
First Edition, 2021

Republic Act 8293, section 176 states that: No copyright shall subsist in any work of
the Government of the Philippines. However, prior approval of the government agency or office
wherein the work is created shall be necessary for exploitation of such work for profit. Such
agency or office may, among other things, impose as a condition the payment of royalties.

Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names,
trademarks, etc.) included in this module are owned by their respective copyright holders.
Every effort has been exerted to locate and seek permission to use these materials from their
respective copyright owners. The publisher and authors do not represent nor claim ownership
over them.

Published by the Department of Education

Development Team of the Module

Writer: April Aime Z. Sordilla
Editors: Honey Lynne Boyles, Maybelle G. Isidoro, Noel G. Escobal
Reviewer: Mylene G. Coquilla
Management Team:
Josephine L. Fadul – Schools Division Superintendent
Melanie P. Estacio - Assistant Schools Division Superintendent
Christine C. Bagacay – Chief – Curriculum Implementation Division
Honey Lynne A. Boyles – Education Program Supervisor – Science
Lorna C. Ragos - Education Program Supervisor
Learning Resources Management
Jecson L. Oafallas – Project Development Officer II

Printed in the Philippines by ________________________

Department of Education – Region XI

Office Address: ___________________________

Telefax: ___________________________

E-mail Address: ___________________________

 11

Physical Science
Quarter 4 – Module 1
Astronomy Before the Advent of
the Telescope
Introductory Message
This Self-Learning Module (SLM) is prepared so that you, our dear
learners, can continue your studies and learn while at home.
Activities, questions, directions, exercises, and discussions are
carefully stated for you to understand each lesson.
Each SLM is composed of different parts. Each part shall guide
you step-by-step as you discover and understand the lesson
prepared for you.
Pre-tests are provided to measure your prior knowledge on lessons
in each SLM. This will tell you if you need to proceed on completing
this module or if you need to ask your facilitator or your teacher’s
assistance for better understanding of the lesson. At the end of
each module, you need to answer the post-test to self-check your
learning. Answer keys are provided for each activity and test. We
trust that you will be honest in using these.
In addition to the material in the main text, Notes to the Teacher
are also provided to our facilitators and parents for strategies and
reminders on how they can best help you on your home-based
learning.
Please use this module with care. Do not put unnecessary marks
on any part of this SLM. Use a separate sheet of paper in answering
the exercises and tests. And read the instructions carefully before
performing each task.
If you have any questions in using this SLM or any difficulty in
answering the tasks in this module, do not hesitate to consult your
teacher or facilitator.
Thank you.

ii
 Let Us Learn!

The stars and other heavenly bodies are a remarkable sight

especially at nighttime. The ancient Greeks had been fascinated by these
objects and the sky and studied them with their own naked eye!

In this module, we will look back at how astronomers learned about

certain astronomic phenomena before the advent of the telescope. At the end
of this lesson, you will be able to:

1. explain how the Greeks knew that the Earth is spherical (S11/12PS-
IVa-38);
2. cite examples of astronomical phenomena known to astronomers
before the advent of telescopes (S11/12PS-IVa-41); and
3. explain how Brahe’s innovations and extensive collection of data in
observational astronomy paved the way for Kepler’s discovery of his laws of
planetary motion (S11/12PS-IVb-44).

Let Us Try!
Let us try to find out if you already have an idea about
astronomic phenomena discovered even before the telescope was
invented.
Multiple Choice

Direction. Identify the choice that best completes the statement or answers
the question.

1. The following observations by the ancient Greeks led them to conclude

that the Earth is round except for one. Which is the exception?
a. The shadow cast by the Earth on a Lunar Eclipse.
b. The shadow cast by the moon on a Solar Eclipse.
c. Ships disappearing as they sail along the horizon.
d. The shape of the moon and the sun.

2. Ancient people observed changes on the appearance of the moon within

how many days?
a. 365
b. 29.5
c. 92.5
d. 7
1
3. Which of the following describes a lunar eclipse?
a. the Earth casts its shadow on the moon
b. the moon casts its shadow on the Earth
c. the moon looks full and bright
d. the moon looks like a half circle

4. When does a solar eclipse occur?

a. when the sun is at the horizon
b. when the sun is at high noon
c. when the Moon is in between the Sun and the Earth
d. when the Sun is between the Moon and Earth

5. Why are planets visible at night?

a. they burn hydrogen and helium only at night
b. the atmosphere is clear during night time
c. planets emit their own light at night time
d. they reflect light from the sun during night time

6.Which of the following was Tycho Brahe’s greatest contribution to

astronomy?
a. his years of careful observations of the planets
b. his model of the universe
c. his discovery of the 3 laws of planetary motion
d. his telescopic observations

7. How does Kepler’s 1st law of planetary motion describe the shape of a
planet’s orbit around the sun?
a. circle
b. ellipse
c. angular
d. irregularly shaped

8. Which of the following is true about Kepler’s 2nd Law of Planetary Motion?
a. A planet intersects the orbit of another planet.
b. The sun moves at an elliptical orbit.
c. A planet moves fastest when it is closest to the sun and slowest when it is
furthest from the sun.
d. A planet moves slowest when it is closest to the sun and fastest when it is
furthest from the sun.

2
9. Which of the following is another name for Kepler’s 3rd Law of Planetary
Motion?
a. Law of Harmonies
b. Law of Ellipses
c. Law of Equal Areas
d. Law of Orbits

10. Which of the following tools did Tycho Brahe used to observe a new star
that appeared in the constellation of Cassiopeia?
a. sextant
b. telescope
c. microscope
d. globe

3
 Let Us Study

THE GREEKS’ PERSPECTIVE OF THE EARTH’S SHAPE

The ancient Greeks knew that Earth was round by observing the arc
shape of the shadow on the Moon during a lunar eclipse.

According to Cudera (2016), around 500 B.C., most Greeks believed

that the Earth was round, not flat. It was Pythagoras and his pupils who were
first to propose a spherical Earth.

In 500 to 430 B.C., Anaxagoras further supported Pythagoras' proposal

through his observations of the shadows that the Earth cast on the Moon
during a lunar eclipse. He observed that during a lunar eclipse, the Earth's
shadow was reflected on the Moon's surface. The shadow reflected was
circular.
Around 340 B.C., Aristotle listed several arguments for a spherical
Earth which included the positions of the North star, the shape of the Moon
and the Sun, and the disappearance of the ships when they sail over the
horizon.
Was there other evidence of Earth's roundness available to people
before the telescope was invented?

What can you observe as the boat moves away from the shore?

4
 ASTRONOMICAL PHENOMENA KNOWN TO ASTRONOMERS
BEFORE TELESCOPE

Even before the invention of the telescope, ancient people have already
observed different astronomical phenomena. The most observable objects in
the sky are the sun and moon (Canoy 2018).

Babylonian and Egyptian civilizations used a primitive version of a

sundial, called gnomon, in systematically observing the motion of the sun. By
looking at the shadows that the gnomon casts, they were able to observe that
the sun rises in the eastern part of the sky, reaches its highest point in
midday, and sets in the western part of the sky.

Also, they recorded that the points where the sun rises and sets on the
horizon varies over a year and these variations happen periodically. They
observed that these variations are related to weather and so concluded that
seasonal changes in climate happen during a course of one year.

Phases of the Moon

Ancient people have observed that the moon changes its path and its
appearance within a period of 29.5 days. They observed that the moon
changes its appearance from thin semi-circular disk to full circular disk.
These phases of the moon is the basis of ancient calendars (Canoy 2018).

Solar and Lunar Eclipses

Besides their observation in the different phases of the moon, they also
noticed that there are times when the moon or part of it seemed to be covered
by a shadow for a brief moment. A lunar eclipse occurs when the Earth casts
its shadow on the moon when the Earth is between the Sun and the Moon.
A phenomenon such as this is known as a lunar eclipse wherein the moon
changes into a dark or blood red color.

Aside from lunar eclipse, the occurrence of a solar eclipse was also
observed. Solar eclipse occurs when the Moon is in between the Sun and the
Earth and the moon partially or completely blocks out the sun (Canoy, 2018).

5
Planets and Stars

When you look at the night sky, you see many tiny lights. If you watch
night after night you would see that most of these tiny lights, that we call
stars, always make the same shapes in the sky, like the Big Dipper. There are
a few shiny objects that seem to move along the stars. These wandering
objects are planets (Cudera 2016).

Both planets and stars are very far away from us; but the planets in
our solar system are much closer to us than all of the stars, except for the
star which we call Sun. Planets are smaller than stars and circle around the
sun. That’s why the planets seem to move among the stars. Astronomers
believe that many stars have planets circling around them, just as the Sun
does. The sun is an average-sized star. This means that some stars are larger
than the Sun, some are smaller, and many are the same size.

To the naked eye, planets look like stars in the night. They reflect light
from the sun. Light from distant stars is usually not as steady as light from
nearer planets. If you didn’t see any twinkling at first, cover one eye or look
at the star from a different angle. If you see twinkling, then you’re looking at
a star.

BRAHE’S OBSERVATIONAL ASTRONOMY AND KEPLER’S

PLANETARY LAWS OF MOTION

Before the telescope has been invented, early astronomers devised

equipment to make accurate observations of the heavenly bodies and collect
important data that would later lead to mathematical calculations on their
motion.

Tycho Brahe (1546-1601) was a

nobleman from Denmark who made astronomy
his life's work because he was so impressed
when, as a boy, he saw an eclipse of the Sun
take place at exactly the time it was predicted.
Tycho's life's work in astronomy consisted of
measuring the positions of the stars, planets,
Moon, and Sun, every night and day possible,
and carefully recording these measurements, Tycho Brahe
year after year.

6
 Tycho wanted to study science so that he could learn how to predict
eclipses. He studied mathematics and astronomy in Germany. Then, in 1571,
when he was 25, Tycho built his own observatory on an island and some
money given by the King of Denmark for the purpose of predicting eclipses.
Tycho named his island observatory Uraniburg-Urania after the muse of
astronomy. He lived and worked in his observatory for until he had a
disagreement with the King of Denmark. Tycho’s main goal was to determine
the positions of the stars and planets as accurately as possible. This could
only be done by constructing precision observing instruments and making
and recording many observations of stars and planets night after night
(Harvard University, 2021)

In November of 1572 Brahe observed a new

star in the constellation of Cassiopeia. With a
sextant and cross-staff he was able to measure the
star's position and became convinced that it was in
the realm of the supposed unmoving fixed stars. This
observation was inconsistent with the longstanding
belief that the celestial realm was a place of perfect
and unchanging fixed stars.
triangular sextant

Alongside this development, the appearance of a comet in 1577

provided additional evidence that things did change and did move in the
celestial sphere. Based on careful measurements, Brahe was able to identify
that the comet was outside the sphere of the moon and he eventually
suggested it was moving through the spheres of different planets.

As a result of these observations, Brahe put forward a new model for

the cosmos. In Brahe's model, all of the planets orbited the sun, and the sun
and the moon orbited the Earth. Keeping with his observations of the new star
and the comet, his model allowed the path of the planet Mars to cross through
the path of the sun.

7
 Many scientists have been critical of Brahe's model as a backward step
in the progress of science. However, it is critical to remember the value that
Brahe's system offered. This system had the advantage of resolving the
problem of stellar parallax. One of the persistent critiques of Copernicus's
model (and even of Aristarchus model in ancient Greece) was that with a
moving Earth one should expect to see parallax movement of the stars. As the
Earth changes position in relationship to that of the stars, one would expect
to see the stars change position relative to each other. Copernicus' answer
was that the stars had to be so distant that it wasn't possible to detect
parallax. Still, the distance required to make this work was so massive as to
be a problem for the system.

This was not a problem for Brahe's system because his model allowed
for the circles in the heavens to intersect. Brahe's model was not a step
backward; but revolutionary in the sense that it was a competing way to make
sense of the data the heavens provided.

Johannes Kepler, born in 1571, made

major contributions to astronomy as his work
mixed sophisticated mathematics and
astronomy with mystical ideas about
astrology. Kepler worked for Tycho Brahe,
publishing an extensive amount of Brahe's data
in Rudolphine Tables. Although he used much
of that data for his own publications Kepler's
work would significantly depart from Brahe's.
Unlike Brahe, Kepler accepted a heliocentric
(sun-centered) model of the universe (Library of
Johannes Kepler Congress, 2021).

First Law of Planetary Motion - The Law of Ellipses

Kepler's first major work, Mysterium Cosmographicum (The

Cosmographic Mystery, 1596), and his later work Harmonice
Mundi (Harmonies of the World, 1619) are both largely concerned with the
order and geometry of the heavens. Kepler's quest to bring together geometry
and physics led to a new shape of the planetary orbits. In Astronomie
Nova (1609), Kepler presented extensive research on the orbit of Mars (Library
of Congress, 2021).

8
 Using Tycho Brahe's observational data, Kepler was able to fine tune
the movements of the planets and demonstrate that the movement of Mars
could be described as an ellipse. An ellipse is a closed curve, like an oval
around two points called foci. It was generally taken for granted that motions
in the heavens would involve only perfect circles. However, through
innovations in mathematics, Kepler was able to mathematically describe
ellipses that closely fit the paths the planets moved through in the heavens.

Alongside describing the elliptical nature of orbits, Astronomie

Nova offered initial arguments for a force of attraction that could organize and
hold this kind of system together. Kepler's work foreshadowed the discovery
of one of the fundamental forces of physics, the law of gravity.

Second Law of Planetary Motion- Law of Equal Areas

Kepler's second law - sometimes referred to as the law of equal areas -

describes the speed at which any given planet will move while orbiting the
sun. The speed at which any planet moves through space is constantly
changing. A planet moves fastest when it is closest to the sun and slowest
when it is furthest from the sun. Yet, if an imaginary line were drawn from the
center of the planet to the center of the sun, that line would sweep out the
same area in equal periods of time. For instance, if an imaginary line were
drawn from the earth to the sun, then the area swept out by the line in every
31-day month would be the same. This is depicted in the diagram below. As
can be observed in the diagram, the areas formed when the earth is closest to
the sun can be approximated as a wide but short triangle; whereas the areas
formed when the earth is farthest from the sun can be approximated as a
narrow but long triangle. These areas are the same size. Since the base of
these triangles are shortest when the earth is farthest from the sun, the earth
would have to be moving more slowly in order for this imaginary area to be
the same size as when the earth is closest to the sun ("Kepler's Three Laws" 2021)

9
Third Law of Planetary Motion

Kepler's third law - sometimes referred to as the law of harmonies -

compares the orbital period and radius of orbit of a planet to those of other
planets. Unlike Kepler's first and second laws that describe the motion
characteristics of a single planet, the third law makes a comparison between
the motion characteristics of different planets. The comparison being made is
that the ratio of the squares of the periods to the cubes of their average
distances from the sun is the same for every one of the planets. As an
illustration, consider the orbital period and average distance from sun (orbital
radius) for Earth and mars as given in the table below (physicsclassroom.com,
n.d.).

Period Average T2/R3

Planet
(s) Distance (m) (s2/m3)
Earth 3.156 x 107 s 1.4957 x 1011 2.977 x 10-19
Mars 5.93 x 107 s 2.278 x 1011 2.975 x 10-19

Observe that the T2/R3 ratio is the same for Earth as it is for mars. In
fact, if the same T2/R3 ratio is computed for the other planets, it can be found
that this ratio is nearly the same value for all the planets. Amazingly, every
planet has the same T2/R3 ratio.

Kepler's third law provides an accurate description of the period and

distance for a planet's orbits about the sun. Additionally, the same law that
describes the T2/R3 ratio for the planets' orbits about the sun also accurately
describes the T2/R3 ratio for any satellite (whether a moon or a man-made
satellite) about any planet ("Kepler's Three Laws" 2021).

10
 Let Us Practice

Activity 1. Illustrating Earth’s Shadow during Lunar Eclipse

A. Draw an illustration of the Earth’s shadow during lunar Eclipse on

the box below.

B. Explain how the shape of the Earth’s shadow on the Moon proves
that the Earth is round.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

Activity 2. Phases of the Moon

Do you still remember the phases of the moon? Shade the circles
appropriately for each phase of the moon.

11
 Activity 3. Solar and Lunar Eclipse

Can you distinguish which of the following pictures show a Solar and
Lunar Eclipse? Write your answers on the line provided below the picture.

Activity 4. Compare and Contrast Planets from Stars

Based on the given information, complete the diagram to help you tell
stars apart from planets in the night sky.

PLANETS STARS

Activity 5. Kepler’s Third Law of Planetary Motion

Using the formula T2/R3, calculate the ratio on a separate sheet of paper
and write your answers on the blanks.

Period Average T2/R3

Planet
(yr) Distance (au) (yr2/au3)
Mercury 0.241 0.39 _________
Venus .615 0.72 _________
Earth 1.00 1.00 _________

12
 Mars 1.88 1.52 _________
Jupiter 11.8 5.20 _________
Saturn 29.5 9.54 _________
Uranus 84.0 19.18 _________
Neptune 165 30.06 _________
Pluto 248 39.44 _________

What do you observe with your answers? How does it prove the Law of
Harmonies?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

(NOTE: The average distance value is given in astronomical units where 1 a.u. is equal
to the distance from the earth to the sun - 1.4957 x 1011 m. The orbital period is given
in units of earth-years where 1 earth year is the time required for the earth to orbit the
sun - 3.156 x 107 seconds.)

Let Us Remember

Awesome! Now, let us gather what we have learned.

Activity 6. Complete the Summary!

A. Fill in the blanks with words that will make the sentences/paragraphs
correct.

The ancient Greeks learned that the Earth was round because of the
shape of the shadow it casts during a ____________________. Another Greek
philosopher named __________________ observed that ships disappear as they
sail along the horizon.

Ancient astronomers observed the changes in the appearance of the

moon within _________ days. A __________________ occurs when the Earth
casts its shadow on the moon when the Earth is between the Sun and the
Moon. On the other hand, a ___________________ occurs when the Moon is in
between the Sun, the Earth, and the moon partially or completely blocks out
13
the sun. Astronomers believe that many _____________have planets circling
around them, just as the Sun does.

_____________________ developed tools such as a sextant in order to

observe the heavenly bodies and get accurate data describing them. He
discovered that the universe is changing with the appearance of a new star in
a constellation called _______________ and the appearance of a comet.

Johannes Kepler, a mathematician formulated the Laws of Planetary

Motion. The first law explains that the shape of a planet’s orbit around the
sun is an _____________ and not a perfect circle. The second law of planetary
motion states that a planet moves fastest when it is ___________ to the sun
and slowest when it is ____________ from the sun. The third law of planetary
motion states that the ratio of the ____________ of the periods to the
____________ of their average distances from the sun is the same for every one
of the planets.

B. Answer the questions that follow.

1. What instruments did Tycho Brahe used when he observed a new star in the
constellation of Cassiopiea?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

2. Despite working for Tycho Brahe, how did Kepler’s perspective of the
universe differ?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

3. Describe the shape of a planet’s orbit according to Kepler’s First Law of

Planetary Motion.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

14
4. How did Brahe’s innovations and extensive collection of data in
observational astronomy pave the way for Kepler’s discovery of his laws of
planetary motion?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

5. Explain why Kepler’s 2nd Law of Planetary Motion also called Law of Equal
Areas?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

6. What is the relationship of the square of the periods and the cube of the
distances of all planets that revolve around the sun according to the Law of
Harmonies?

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

Let Us Assess

Superb! Just Superb! It’s time to try the fruit of our journey!
Multiple Choice
Direction. Identify the choice that best completes the statement or answers
the question.

1. When does a solar eclipse occur?

a. when the sun is at the horizon
b. when the sun is at high noon
c. when the Sun is between the Moon and Earth
d. when the Moon is in between the Sun and the Earth

15
2. Which of the following states that the orbit of planets revolving around
the sun takes a shape of an ellipse?
a. Law of Equal Areas
b. Law of Ellipses
c. Law of Harmonies
d. Universal Law of Gravitation

3. The following observations by the ancient Greeks led them to conclude

that the Earth is round except for one. Which is the exception?
a. the shape of the moon and the sun
b. the shadow cast by the moon on a Solar Eclipse
c. the shadow cast by the Earth on a Lunar Eclipse
d. ships disappearing as they sail along the horizon

4. Which of the following phenomena is described when the moon changes

into a dark or blood red color?
a. solar eclipse
b. solar solstice
c. lunar eclipse
d. vernal equinox

5. Which of the following happens when the Earth casts a shadow on the
moon?
a. Summer Solstice
b. Vernal Equinox
c. Solar Eclipse
d. Lunar Eclipse

6. Why are planets visible at night?

a. planets emit their own light at night time
b. the atmosphere is clear during night time
c. they burn hydrogen and helium only at night
d. they reflect light from the sun during night time

7. Which of the following devices did Babylonians and Egyptians used to

systematically observe the motion of the sun through shadows?
c. globe
b. gnomon
a. telescope
d. sextant

8. Which of the following was Tycho Brahe’s greatest contribution to

astronomy?
a. his model of the universe
b. his telescopic observations
c. his years of careful observations of the planets
d. his discovery of the 3 laws of planetary motion
16
9. Which of the following is true about Kepler’s 2nd Law of Planetary Motion?
a. The sun moves at an elliptical orbit
b. A planet intersects the orbit of another planet
c. A planet moves fastest when it is closest to the sun and slowest when it is
furthest from the sun.
d. A planet moves slowest when it is closest to the sun and fastest when it is
furthest from the sun.

10. The following astronomers proposed a round shaped Earth EXCEPT for
one. Which is the exception?
a. Lucretius
b. Aristotle
c. Pythagoras
d. Anaxagoras

11. Using the formula T2/R3 of the 3rd Law of Planetary Motion, what will be
the ratio for planet Uranus with a period of 0.84 years and a distance of
19.18 au?
a. 0.98
b. 9.80
c. 1.00
d. 0.01

12. Which of the following is another name for Kepler’s 3rd Law of Planetary
Motion?
a. Law of Orbits
b. Law of Ellipses
c. Law of Harmonies
d. Law of Equal Areas

13. Ancient people observed changes on the appearance of the moon within
how many days?
a. 7
b. 29.5
c. 92.5
d. 365

14. Which of the following tools did Tycho Brahe used to observe a new star
that appeared in the constellation of Cassiopeia?
a. globe
b. sextant
c. telescope
d. microscope

17
15. Which of the Laws of Planetary Motion states that the ratio of the squares
of the periods to the cubes of their average distances from the sun is the same
for every one of the planets?
a. Law of Ellipses
b. Law of Harmonies
c. Law of Equal Areas
d. Universal Law of Gravitation

Let Us Enhance

Activity 7. Crossword Puzzle

Complete the crossword puzzle below.

1 2
3 4

5 6

9
10

18
 Let Us Reflect

Congratulations! You may want to share your deep thoughts on this!

Activity 8. My Thoughts Journal

Organize your thoughts by answering the following end of the module
questions:
1. Which of the topics interest you the most? Why?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

2. Which of the topics interest you the least? Why?

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

3. Did the activities help you understand the topic (Y/N)? Explain your
answer.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

4. Did you see the significance/ connection of the topic to the current
understanding about the universe?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

19
Answer key

Activity 1

20
21
 References

Cudera, Rizalyn (et.al). 2016. Physical Science for Senior High School. Mutya
Publishing House.

De Villa, Rocelia M. 2016. Exploring Natural Science: Physical Science Senior

High School. Don Bosco Press

Moncada, Ma. Noemi M. 2016. Physical Science for Senior High School.
Educational Resources Corporation

CK-12. “Earth’s Shape”. Accessed June 15, 2020.

https://www.ck12.org/earth-science/earths-shape/lesson/Earths-
Shape-HS-ES/
Canoy, Warlito. “Lesson 6.3 How the Greeks Knew that the Earth was Spherical”.
Accessed June 15, 2020. https://www.facebook.com/notes/grade-11-
physical-science/lesson-63-how-the-greeks-knew-that-the-earth-is-
spherical/2033007150048833/
Library of Congress. “Whose Revolution? Copernicus, Brahe, Kepler. Accessed
June 15, 2020. https://www.loc.gov/collections/finding-our-place-in-
the-cosmos-with-carl-sagan/articles-and-essays/modeling-the-
cosmos/whose-revolution-copernicus-brahe-and-kepler
Harvard University. “Ice Core Records- From Volcanoes to Supernovas”.
Accessed June 16, 2020.
https://chandra.harvard.edu/edu/formal/icecore/The_Astronomers_
Tycho_Brahe_and_Johannes_Kepler.pdf
The Physics Classroom. Kepler’s Three Laws. Accessed June 16, 2020.
https://www.physicsclassroom.com/class/circles/Lesson-4/Kepler-s-
Three-Laws

22
For inquiries or feedback, please write or call:

Department of Education – Division of Tagum City

Office Address: Energy Park, Apokon, Tagum City, 8100

Telefax: (084) 216-3504

Email Address: tagum.city@deped.gov.ph

23