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How a stick's shadow measured the whole Earth: Eratosthenes, a well and 5,000 stadia Two sticks, one shadow and one distance were enough for Eratosthenes to size the whole planet around 240 BC. On the summer solstice the noon Sun shone straight… History4 min read How a stick and a well measured the whole Earth: Eratosthenes Around 240 BC, the librarian Eratosthenes measured the size of the Earth using a well, a stick and a shadow. At noon on the summer solstice the sun shone… History4 min read How a 2,000-year-old bronze machine predicted eclipses with the number 223 In 1901, divers pulled a corroded bronze machine from a shipwreck off the Greek island of Antikythera. One dial ended in the number 223, written in Greek… History4 min read How Eratosthenes measured the whole Earth with a stick and a shadow Around 240 BC, Eratosthenes, head of the Library of Alexandria, measured the size of the whole Earth with a stick and a shadow. At noon on midsummer, sticks in… History4 min read