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Astronomy in history

Ancient Greeks

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.

Next:  Hipparchus and Ptolemy

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Claudius Ptolemaeus 90-168 A.D. (also known as Ptolemy). A medieval artist's idea of how he might have looked.

Are you as clever as the Greeks?

Venus is closer to the Sun than the Earth is. Use this information to create an explanation of why it is impossible to see Venus in the middle of the night.  It helps to draw at least one sketch.

If you enjoyed(?) that challenge, try to do the same for phases of the Moon. That is, explain why it seems to change shape in the sky in monthly cycles.