Thursday, February 19, 2009

February 19: Nicolaus Copernicus

Nicolaus Copernicus
February 19, 1473 – May 24, 1543

Nicolaus Copernicus was the first astronomer to formulate a scientifically-based heliocentric cosmology that displaced the Earth from the center of the universe. His epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), is often regarded as the starting point of modern astronomy and the defining epiphany that began the Scientific Revolution.

Although Greek, Indian and Muslim savants had published heliocentric hypotheses centuries before Copernicus, his publication of a scientific theory of heliocentrism, demonstrating that the motions of celestial objects can be explained without putting the Earth at rest in the center of the universe, stimulated further scientific investigations and became a landmark in the history of modern science that is known as the Copernican Revolution.

Among the great polymaths of the Renaissance, Copernicus was a mathematician, astronomer, physician, classical scholar, translator, artist, Catholic cleric, jurist, governor, military leader, diplomat and economist. Among his many responsibilities, astronomy figured as little more than an avocation — yet it was in that field that he made his mark upon the world.

Early traces of a heliocentric model are found in several anonymous Vedic Sanskrit texts composed in ancient India before the 7th century BCE. Additionally, in the sixth century the Indian astronomer and mathematician Aryabhata anticipated elements of Copernicus's work, although he did not maintain heliocentrism.

Aristarchus of Samos in the 3rd century BCE elaborated some theories of Heraclides Ponticus (the daily rotation of the Earth on its axis, the revolution of Venus and Mercury around the Sun) to propose what was the first scientific model of a heliocentric solar system: the Earth and all other planets revolving around the Sun, the Earth rotating around its axis daily, the Moon in turn revolving around the Earth once a month. His heliocentric work has not survived, so we can only speculate about what led him to his conclusions. It is notable that, according to Plutarch, a contemporary of Aristarchus accused him of impiety for "putting the Earth in motion".

Copernicus cited Aristarchus and Philolaus in a surviving early manuscript of his book, stating: "Philolaus believed in the mobility of the earth, and some even say that Aristarchus of Samos was of that opinion." For reasons unknown (possibly from reluctance to quote pre-Christian sources), he did not include this passage in the published book. It has been argued that in developing the mathematics of heliocentrism Copernicus drew on not just the Greek, but also the work of Muslim astronomers, especially the works of Nasir al-Din Tusi (Tusi-couple), Mo'ayyeduddin Urdi (Urdi lemma) and Ibn al-Shatir. In his major work, Copernicus also discussed the theories of Ibn Battuta and Averroes.

The Lunar crater Copernicus is named in his honor.


  1. One of my heroes! When I was a kid I did my first class talk on Copernicus and astronomy. You have a really neat blog!


  2. Thanks, RR. I've always had a love of history and when I developed a passion for astronomy, the two merged...