Monday, August 28, 2006

How We Learned the Earth is Round

As we begin our study of American History, Truthquest (our "spine") begins with the explorers. We have been studying the explorers for a few weeks and have discussed how people used to believe the earth is flat, but then they discovered it was round.

About 2,500 years ago, the Greeks discovered that the earth must be round. They based this both because of how boats look as the sail over the horizon and because of the curved shape they saw on the moon during a lunar eclipse. A great book describing this discovery is How We Learned the Earth is Round by Patricia Lauber.

The book also describes how a Greek measured the circumference of the earth. This was done over 2,000 years ago by Eratosthenes. The Librarian Who Measured the Earth by Kathryn Lasky is a great book which tells this this story, although the last few pages get pretty detailed.

In the late 1400's, Columbus believed the earth was round and wanted to sail west, instead of east, to reach the Indies. A good book about Columbus is A Picture Book of Christopher Columbus by David A. Adler.

Then, Magellan believed he could sail all the way around the earth. He didn't survive the 3-year trip, but some of his crew did and thus they proved that the earth is round. It's a longer book, but we are enjoying Who Was Ferdinand Magellan? by Sydelle Kramer.

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