Theory question 204
The Earth and Solar System(a) Name any four planets in the solar system. (b) With the aid of appropriate diagrams, explain three proofs to show that the earth is spherical in shape.
Show the model answer
Model answer
(a) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
(b) Ship's visibility: an approaching ship shows its mast/smoke first and the hull last (diagram of curved sea surface); circular horizon that widens with height; circumnavigation: travelling continuously in one direction brings one back to the starting point (Magellan); lunar eclipse: the earth's shadow on the moon is always circular; sunrise and sunset happen at different times at different longitudes; photographs from space; other planets are spherical. Diagrams for each.
Explanation
Each proof needs its own simple diagram.