Historical Developments

Models of the Universe

Ptolemy based much of his work on that of Aristotle and proposed that the earth is the centre of the heavens - a geocentric universe

In Brahe's model:-All the planets, with the exception of the Earth, orbited the sun, -The sun moved around a stationary Earth.

Copernicus thought that the planets orbited the Sun, and that the Moon orbited Earth. The Sun, in the center of the universe, did not move, nor did the stars

Aristarchus’s model was heliocentric. He believed that the Earth rotated on its axis

His model was geocentric, He also believed that the sun and the stars were in a celestial sphere that rotated around earth.

Kepler discovered that the planets move on an elliptical orbits, and developed his three laws, published between 1609 and 1621