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Saturday, October 5, 2013

Pythagoras estimated the earth to be round

While we often think of Copernicus as discovering the Earth is round, the truth is this wisdom was known long before his time.  The discovery that the Earth is round may actually go as far back as Ancient Babylonia or Ancient Egypt, yet the wisdom was kept esoteric for fear of death.

The first known person to theorize the earth is round was Pythagoras.  He believed the universe consisted of "ten spheres: the sun, the moon, Earth, Mercury, Venus, Mars, Jupiter, Saturn, the counter Earth, and the central hearth.  The invisible central hearth is the center of the universe.  Everything comes from this sphere.  The counter Earth can't be seen from Earth because it's on the opposite side of the central earth."  (1, page 26-7)

The idea that the earth is round was new to the Greeks, so they out right rejected it.  And, for the most part, Pythagoras kept this knowledge to himself.  Pythagoras was well respected, so his "controversial" claims were often just disregarded by men during his day.  Yet now as we look back we can give him the credit he deserves.

Pythagoras used mathematical formulas (something else new to Greece, and rejected during the life of Pythagoras) to prove the earth was round.  Some of his followers used his mathematical formulas to calculate estimates for both the circumference of the earth and the distance to the moon.

Around 280 B.C. Aristarchus, a Greek Astronomer, calculated the approximate size of the moon.  He used the size of the lunar shadow's arc, plus the known rules of geometry.  He estimated the moon to be a third the size of earth, and he was close: the moon is a quarter the size of earth

Eratosthenes estimated the size of earth measuring the shadows of two sticks in Syene, Egypt and Alexandria, Egypt.  He estimated the Earth's circumference to be 250,000 miles.  That's pretty close to the actual 238,855 miles.

So there's some wisdom you can share the next time such a subject comes up in a conversation with one of your patients. Gotta love history.

  1. Harkins, Susan Sales and William H. Harkins, "Biography from Ancient Civilizations, Legends, Folklore, and Stories of Ancient Worlds: The Life and Times o Pythagoras," 2007, Mitchell Lane Publishers

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