Ancient Astronomy.pptx

The Shape of the
Earth is Round
By: X-handi B. Fallarna

The shape of the Earth is round, just round
Round, just round
Round, just round
The shape of the Earth is round, just round
All this time
The Greek philosophers had thought it’s flat,
Some thought it’s round, some thought it’s round
The Greek philosophers had thought it’s flat,
But they got it wrong!
North Star, eclipse, and sailing ship,
Moon’s shadow from Earth’s relationship
These conclude that the Earth is round
All this time!
7 1/26/2024 Add a footer

• Oblate spheroid: the shape of the Earth. It has bulging equator and
squeezed poles.
• Solstice: either of the two times in the year, the summer solstice and the
winter solstice, when the sun reaches its highest or lowest point in the
sky at noon, marked by the longest and shortest days.
• Eclipse: an obscuring of the light from one celestial body by the passage
of an other between it and the observer or between it and its source
of illumination.
• Heliocentrism: the astronomical model in which the Earth and planets
revolve around the Sun.
• Geocentrism: any theory of the structure of the solar system (or the
universe) in which Earth is assumed to be at the center of it all.

Have you ever wondered what the
philosophers in ancient astronomy
thought about the shape of the Earth?

And the Shape Is…
1. The class will be divided into four groups.
2. Each group will perform the task which is to find out the shape of the shadow.
3. Using the materials, such, actual flashlight or use the flashlight app of the mo-bile phone (if both
materials are not readily available), -Two spherical objects; 1-big, 1-small, ruler
4. They will execute the activity in a collaborative manner.
5. After the allotted time, each group will present their output in a creative way. It can be through a
song, a role play, poem, poster, or interpretative dance.A 5-minute-performance will be evaluated
using the following criteria.
• Criteria:
Accuracy …………………… 40
Presentation/Organization …………………... 30
Creativity …………………… 20
Timeliness …………………… 10
TOTAL 100

Procedure:
1. Align the flashlight and the balls
horizontally.
2. Point the flashlight to one of the balls.
3. Observe the shadow it casts on the ball
behind it.

• What is the shape of the shadow cast by Ball 1?
• Which of the two balls represents the Earth? the Moon?
• Supposed that the moon or Earth is a heart shape, what shadow would it form when
sunlight is aligned with it?Why?
• How is the result of the experiment related to the arguments about the shape of the Earth?
• If you use a different object, like two Rubik’s cubes instead of ping pong balls, will it cast the
same shape of shadow? Explain.
• Can you provide myths and legends about the Moon, eclipse, etc.in your community, in
Busuanga?
• Who are the philosophers in ancient astronomy thought about the shape of the Earth?
• How does understanding of astronomy, specifically the shape of the Earth helps you
understand the Earth today?
• Why do you have to conduct the experiment or activity?
• How will you relate it in a real-life situation?
• How will you show the appreciation of scientific progress in terms of observation,
exploration and discovery?

Ancient
Astronomy
Learning Competency & Code:
Explain how the Greeks knew that the
Earth is spherical (S11/12PS-IVa-
38)

•"Around 500 B.C., 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.

North Star
•The North Star was believed to be at a
fixed position in the sky. However, when
the Greeks traveled to places nearer the
equator, like Egypt, they noticed that the
North Star is closer to the horizon.

The Shape of the Sun and the Moon
•Aristotle argued that if the
Moon and the Sun were both
spherical, then perhaps, the
Earth was also spherical.

Disappearing Ships
•If the Earth was flat, then a ship traveling
away from an observer should become
smaller and smaller until it disappeared.
However, the Greeks observed that the
ship became smaller and then its hull
disappeared first before the sail as if it was
being enveloped by the water until it
completely disappeared

The Size of the Spherical Earth
•Eratosthenes gave the most accurate size
during their time.While he was working at the
Library of Alexandria in Northern Egypt, he
received correspondence from Syene in
Southern Egypt which stated that a vertical
object did not cast any shadow at noontime
during the summer solstice.

Important
Findings of
the Following
Greek
Astronomers
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a. Anaxagoras
 Anaxagoras was able to explain what causes
the phases of the moon. According to him,
the moon shone only by reflected sunlight.
Since it is a sphere, only half of it
illuminated at a time. This illuminated part
that is visible from the earth changes
periodically.

b. Eudoxus
Eudoxus proposed a system of fixed
spheres. He believed that the Sun, the
moon, the five known planets and the
stars were attached to these spheres
which carried the heavenly bodies while
they revolved around the stationary
Earth.

c. Aristotle
Aristotle was a student of Plato. For him,
the earth is spherical in shape since it
always casts a curved shadow when it
eclipses the moon. He also believed that
the earth was the center of the universe.
The planets and stars were concentric,
crystalline spheres centered on the
earth.

d. Aristarchus
 Aristarchus is the very first Greek to profess the
heliocentric view. The word helios means sun;
centric means centered. This heliocentric view
considered the sun as the center of the universe. He
learned that the sun was many time farther than the
moon and that it was much larger than the earth.
He also made an attempt to calculate the distance
of the sun and the moon by using geometric
principles. He based his calculations on his
estimated diameters of the earth and moon, and
expressed distance in terms of diameter.

e. Eratosthenes
The first successful attempt to determine the
size of the earth was made by him. He did this
by applying geometric principles. He observed
the angles of the noonday sun in two Egyptian
cities that were almost opposite each other-
Syene (now Aswan) in the south and
Alexandria in the north. He assumed they
were in the same longitude.

f. Hipparchus
 Hipparchus is considered as the greatest of the early
Greek astronomers. He observed and compared the
brightness of 850 stars and arranged them into order
of brightness or magnitude. He developed a method
for predicting the times of lunar eclipses to within a
few hours. Aside from this, he also measured the
length of the year to within minutes of the modern
value.

g. Claudius Ptolemy
He believed that the earth was the
center of the universe. His Ptolemic
Model claimed that the planets moved
in a complicated system of circles. This
geocentric model also became known as
the Ptolemic System.

The Ptolemic Model
 Claudius Ptolemy developed a model that was able
to explain the observable motions of the planets.

Of all the arguments presented by the
Greeks as proof that the Earth is spheri-
cal, which among you find more
convincing? Why?
Think – Pair - Share

Multiple
Choice:
Choose the letter of
the BEST and
CORRECT answer.

Answer key:
1. B
2.A
3. A
4.D
5. C

ASSIGNMENT:
If you were given a chance to
write something on your journal
for your chosen Greek philosopher,
who will it be and what will you
tell him about his findings on
ancient history?

Ancient Astronomy.pptx

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