There was a time when people thought that the Earth was at the center of our solar system. We know today that it isn’t, but the first man to realize and document this discovery was the astronomer and mathematician Nicolaus Copernicus.Today would have been his 540th birthday, and Google is celebrating it with an animated Google Doodle on its homepage. The Doodle is of Copernicus’ heliocentric model, which shows the planets orbiting around the Sun.Copernicus began working on his heliocentric theory at some point between 1503-1510 when working as his uncle’s secretary in Poland. He finished the first 40-page draft, entitled Commentariolus, in 1514. He then continued to work on it making revisions up until 1532 when the theory was effectively completed and named De Revolutionibus Orbium Coelestium, or On the Revolutions of the Celestial Spheres.Such a theory was sure to be controversial at the time, and so Copernicus delayed its printing. In the meantime, word of it spread to both educated people across Europe and the Pope, all of whom wanted to know more and for him to print his work. But it wasn’t until 1542, after pressure from his then pupil Rheticus, that he agreed to let it be published.Before the year was over Copernicus became very ill and died, but apparently not before being handed an advanced copy of the Revolutions book. Little did he know he would be added to the history books as helping to further our knowledge of the solar system and Earth’s place within it.