7 Early Models Of The Solar System

Question 1

What is Precession?

Answer 1

Precession is the circular motion of the axis of something that is rotating

Question 2

Why do some ancient monuments seem random?

Answer 2

The current celestial alignments differ from the original alignments of the monuments because the Earth’s axis of rotation isn’t fixed; it precesses

Question 3

What were the ancient models of the Solar System?

Answer 3

Aristotle and Plato models suggested a geocentric system with the Earth at the centre of the Solar System

Question 4

What were the issues with the Geocentric system?

Answer 4

The Geocentric system had an inability to explain the observed retrograde motion of the planets

Question 5

How was the geocentric system developed to explain retrograde motion?

Answer 5

Each planet was placed on a small rotating circle (an epicycle) whose centre revolved around the Earth on another circle (the deferent)

Question 6

How did Ptolemy adjust the epicycle system?

Answer 6

Ptolemy put the Earth slightly off-centered and an imaginary point called the Equant from which the angular motion of the centre of each epicycle was uniform

Question 7

What is the Heliocentric system?

Answer 7

The Heliocentric system is a model that suggested the Sun was at the centre of the solar system

Question 8

Who was the first person to suggest a Heliocentric system?

Answer 8

Archistarchus of Samos argued for a Heliocentric system in c.270 BCE based on his calculations that the Sun was much larger than the Earth
However, the theory was only recognized as a real hypothesis from Nicholas Copernicus who applied mathematical modelling

Question 9

What did Galileo Galilei do in 1609?

Answer 9

Galileo used the first telescope to observe the sky. He provided evidence for the Heliocentric theory:

• The apparent size of the Planet Venus changed and showed phases
• Four Moons that orbited Jupiter