Thales' model of the Universe

Demonstration

The early Greek philosopher Thales, in about 600 BC, proposed a model to explain the daily motion of the stars. You can demonstrate it using an umbrella.

Apparatus and Materials

• Umbrella, plain black

Health & Safety and Technical Notes

Make sure umbrella is in good condition and no ribs are exposed at its edges.

Read our standard health & safety guidance

Procedure

1. Mark some constellations on the underside of the umbrella and rotate it slowly by the handle in an anticlockwise direction over a flat disc, which represents the Earth. Make sure that students can see the stars on the underside.

Teaching Notes

• See guidance note

  Early astronomical observations

• Thales described a simple model of a small flat Earth surrounded by a sheet of water, with a single vast sphere. This sphere carried the stars and revolved daily round an axis through the ‘Pole Star’. The model made no explanation of the extra motions of the Sun, Moon and planets, except that they must crawl backwards on the inner surface of the sphere.
• The umbrella represents the sphere of the heavens. When the umbrella is opened the ferrule represents the Pole Star. If there are eight ribs they provide a useful marking guide, since pairs of ribs enclose 45°, or three hours of time in a daily revolution.

This experiment was safety-tested in April 2007.