Nicolaus Copernicus, Astronomer

1473: Nicolaus Copernicus, astronomer, mathematician, church canon, governor, administrator, jurist, astrologer and doctor, was born on this day in 1473 in Poland, then Royal Prussia. He proposed a heliocentric theory of the solar system, meaning that the planets revolve around the Sun as the fixed point and that Earth is a planet which also turns once daily on its own axis. His discoveries completely overturned the traditional geocentric theory and is the fundamental starting point of modern astronomy. He published his theory in the book De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Bodies).