Nicolaus Copernicus, whose 540th birthday is celebrated on Google's homepage Tuesday, kicked off the Scientific Revolution.
It's astonishing to think that anatomically modern humans walked on this planet for nearly two hundred millennia before they realized that it was moving.
Then again, you can't really blame us. Even though the equator is spinning at more than a thousand miles per hour, even though our planet is hurtling around our sun at about 66,000 miles per hour, even though our solar system and everything in it is careening around our galaxy at nearly half a million miles per hour, and even though our galaxy is whirling through space at a mind-blowing 1.2 million miles an hour, the very fact that you're not currently clinging to the ground for dear life makes it only natural to think of the Earth as 16th century astronomer Tycho Brahe did, as a "hulking, lazy body, unfit for motion."
Nicolaus Copernicus's book, titled "On the Revolutions of the Heavenly Spheres," was published the year the Polish astronomer died, in 1543. It marked the beginning of an eclipse of a worldview dominated by the ideas of Aristotle, who believed that the Earth remained at rest while the sun, moon, other planets, and all the stars, which were made of an unchanging substance called aether, revolved around it in perfect circles.
Of course nothing is ever that simple. Our prehistoric ancestors observed five celestial bodies moving independently from the rest of the lights in the sky. These bodies would move slowly across the sky, loop backward for a few months, and then loop forward again. The ancient Greeks called them astēr planētēs, or "wandering stars," and thought them to be living beings.
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