Theory question 202
The Earth and Solar System(a) What is the shape of the earth? (b) With the aid of appropriate diagrams, give four proofs to support your answer in (a) above
Show the model answer
Model answer
(a) The earth is spherical (strictly a geoid/oblate spheroid, flattened at the poles).
(b) Any four, each with a diagram: ship's hull disappears first and mast last over the horizon; circular shadow of the earth on the moon during a lunar eclipse; sunrise and sunset happen at different times east and west; circumnavigation (going round the world and returning to the start); the horizon looks circular and widens with height; photographs from space; other heavenly bodies are spherical.
Explanation
Each proof needs a simple labelled diagram.