Tag Archives: Aswan

How Eratosthenes calculated the Earth’s circumference

In 240 BC, the Greek astronomer, geographer, mathematician, music theorist and librarian Eratosthenes of Cyrene (c. 276 BC – c. 195/194 BC) calculated the circumference of the Earth without leaving Egypt. Here’s how:
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Top 10 driest places on Earth

Earth, the blue planet: the oceans combined with the atmosphere makes the planet look blue. So its color mainly comes from water. About 71% of the Earth’s surface is covered with water, in fact Earth is still the only planet we know where water can exist in liquid form on the surface. Water is also vital for all known forms of life. But there are numerous places on Earth that receive rainfall less than even 0.76 mm annually. One place even receive absolutely no rainfall. Here are the top ten driest places on Earth.
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