Daily Quiz for March 16, 2010

Eratosthenes, a Greek mathematician, concluded around 250 BC the earth must be round because shadows of poles at the same time of day were different in two towns. Calculating the poles’ angle to their shadows and using the distance between the cities as a base, he determined the earth’s diameter was 7,850 miles (12,633 km). He was almost right – the earth’s diameter at the equator is 7,926 miles (12,757 km).