February 19, 1473. Nicolaus Copernicus, a Renaissance astronomer and mathematician, was born on this day in Thorn, Poland. At a time when deeply entrenched beliefs placed the Earth at the center of the universe – nested within crystal spheres – he proposed the revolutionary idea that Earth revolves around the sun. Can you picture the leap of imagination required for him to conceive of a sun-centered universe? His book – “De revolutionibus orbium coelestium” (“On the Revolutions of the Celestial Spheres”) – was published just before his death in 1543. It set the stage for all of modern astronomy.
Today, people speak of his work as the Copernican Revolution.
Copernicus wasn’t the first to conceive of a sun-centered universe. Early Greek philosophers also spoke of it.
It was the Greek philosopher Aristotle, however, who proposed that the heavens were literally composed of 55 concentric, crystalline spheres to which the celestial objects were attached.
In Aristotle’s model, Earth lay at the center of these spheres.
Thus Earth lay – fixed and enclosed – until Copernicus published his version of a heliocentric, or sun-centered, universe.
Bottom line: Nicolaus Copernicus proposed that the sun, not the Earth, was at the center of the universe. He was born on this date, February 19, in 1473.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.