prize7-4, Exercise 1: The size of the Earth and the case for Columbus

Model answer (check the details):

The dispute: most informed scholars accepted a larger Earth than Columbus did, close to the figure from Eratosthenes, and so expected the voyage west to Asia to be too long for the ships of the time. Columbus argued for a smaller Earth and a larger Asia, using figures in the tradition of Ptolemy and others, which made the distance seem short enough.

Effect: the scholars' objection was about distance and supplies, not about the shape of the Earth. Columbus was wrong about the size, and he was saved by an unexpected continent in the way.

Lesson: a wrong estimate can underlie a bold plan, and the disagreement shows why sources and numbers need to be checked.