ERATOSTENES

ERATOSTHENES

 Few days ago at class we were speaking about this caracter and I thought that will be interessant do a little search of he.

Eratosthenes was born in Cyrene (Libya) in 276 BC. He was astronomer, historian, geographer, philosopher, poet, mathematician and theater critic. He studied in Alexandria and Athens. He worked with math problems, such as duplication of the cube and prime numbers. He wrote many books which only have news for references of other authors.

One of his main contributions to science and astronomy was his work on the measurement of Earth. Eratosthenes in his studies of the papyri of the library of Alexandria, found a report of observations in Siena, about 800 km. Southeast of Alexandria, where he said that the Sun's rays to fall on a rod midday of the summer solstice, the current June 21, had no shadow.

Eratosthenes then made the same observations in Alexandria the same day at the same time, discovering that the Sun was vertically in a well of water the same day at the same time. He assumed correctly that if the Sun was at a great distance, its rays reach the earth should arrive at the same time, if this was flat as he believed in those times, and you should not find differences between the shadows cast by objects at the same time of the same day, regardless of where you will find.

However, to demonstrate that if they did, he deduced that the Earth was not flat, and using distance known between the two cities and the measured angle of shadows, calculated the circumference of the Earth at approximately 250,000 stadia, about 40,000 kilometers, fairly accurate for the time and resources.

 

This is a image from his theory

  

It's a photo of him

Sunni