Before the Greeks, people in Africa and the Middle East had already used the motions of the Sun, Moon, planets and stars to develop calendars. That meant that they knew when it was the right time of year for planting crops.
The Babylonians, for example, who lived in what is now southern Iraq, developed sophisticated methods for predicting the motions of objects in the sky.
Ancient Greeks such as Hipparchus and Ptolemy developed the mathematics of geometry that helped them to work out:
- That the Earth is round
- The size of the Earth
- That the morning star and the evening star are the same thing. (They are both the planet Venus.)
- The visible planets move in a plane (an imagined flat surface) and the Earth’s equator makes another plane. The angle between the planes is about 24°.
- That the Moon goes around the Earth
- That the Sun is much further from the Earth than the Moon
- What causes eclipses
However, they attributed the patterns of the fixed stars to actions by one or more of their gods.
Hipparchus and Ptolemy