Single Idea 402

[catalogued under 27. Natural Reality / E. Cosmology / 1. Cosmology]

Full Idea

A lunar eclipse always has a convex dividing line, so, if it is eclipsed by the interposition of the earth, the circumference of the earth, being spherical, is responsible for the shape.

Gist of Idea

The Earth must be spherical, because it casts a convex shadow on the moon

Source

Aristotle (On the Heavens [c.336 BCE], 297b29)

Book Reference

Aristotle: 'On the Heavens I and II', ed/tr. Leggatt,Stuart [Aris and Phillips 1995], p.167