Astronomical history



Astronomical history
Astronomical history
1. Dreamtime story
Complete the sentences:
The Warlpiri Aboriginal people explained a solar eclipse as the result of the moon-man being
threatened by the sun-woman who is pursuing him and catching up. The solar and lunar eclipse
dreamtime stories demonstrate that aboriginal people had an understanding that eclipses were
caused by a relationship between the sun and the moon.
2. Ptolemy
Claudius Ptolemy (85−165) developed a model of the universe.
(a) Use the diagram to describe Ptolemy’s model of the universe.
Ptolemy’s theory of earth place in the universe was called a geocentric model. This
means that he thought that the earth was at the centre of the universe. This also explained to
the people about how in religion “god” had made the earth perfect everything revolving
around them.
(b) Where did Ptolemy place the stars in his model?
In this model Ptolemy places the stars outside of the revolving planets. The sun is an example
being the first star in our solar system and being the furthest away eluding to that the
stars were placed outside of our solar system.
(c) Ptolemy knew that Mars moved across the sky in a looping motion called retrograde motion.
His model explained this motion using epicycles. Use the diagram below left to explain the
idea of epicycles; label the diagram below right where necessary.
Ptolemy was the first astronomer to figure out why planets would revolve backwards. He
called this an epicycle. Planets move in and orbit around the sun and also in a circle on
that line (shown in the second picture). When this epicycle theory happens it is thought
that the earth being on a smaller rotation it catches up on say Mars’s rotation it appears
to the naked eye it is revolving backwards
Retrograde motion
Page 2
3. Copernicus
Nicolaus Copernicus (1473−1543) was a Polish astronomer who proposed a radically different
model of the universe.
List from center of
1. Sun
2. Mercury
3. Venus
4. Earth
5. Mars
6. Jupiter
7. Saturn
(a) Where did Copernicus place the sun in his model?
Copernicus placed the sun in his new theory at the centre of the solar system. He called
this with the help of Galileo a heliocentric model of the universe.
(b) Label the diagram above to show the position of the sun and the six known planets.
(c) How did Copernicus explain day and night and the length of a year using his model?
Copernicus explained that day and night happened when the one side of the earth
rotated and did not face the light of the sun. He explained a year happening when the earth
did a full rotation around the sun.
4. Galileo
Galileo Galilee’s (1564−1642) observations of Jupiter over successive nights revealed four starlike
objects in a line with it. The objects moved from night to night, sometimes disappearing behind or
in front of the planet.
(a) Identify the bodies that Galileo had observed. Galileo observed these four bodes and came
to the conclusion that these where exactly like the earth’s moon and how it rotated. So he
defined them as the four moons of Jupiter
(b) Explain how his observations of Jupiter supported the Copernican model and not the
Ptolemaic model of the universe.
Galileos observations helped strengthen Copernicus heliocentric model by proving that
the four moons of Jupiter were not revolving around the earth but around Jupiter. Later
Isaac Newton came to discover that this was the result of Gravity.

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