9781422283356

system rather than overthrowing it. Yet this was an important step away from the view of the Universe that had held sway for so long. THE SUN-CENTERED UNIVERSE Copernicus believed that his Sun-centered Universe wasn’t just a device for simplifying calculations. He thought the Universe really was like that. Pause for a moment and try to put yourself in the position of someone hearing this idea for the first time. For thousands of years humanity had believed itself to be at the center of creation, and suddenly along had come someone who dared to suggest it wasn’t so. Unsurprisingly, it was not a popular suggestion, especially with the Church. No one at that time willingly made an enemy of the Church, and Copernicus was careful to restrict the circulation of his ideas. He eventually agreed to publish his Revolutions , dedicating it to Pope Paul III. When the book was being printed, a minister named Andreas Osiander added an introduction without Copernicus’s approval. In it he said that these new ideas need not be considered as true! Copernicus had no opportunity to demand a correction; it is said that he received a bound copy of the book when he was on his deathbed. It was several decades before people discovered that Copernicus hadn’t written the introduction. THE NEW STAR For some time nothing changed. Many astronomers carried on working with the old, familiar system. Yet word of the new Copernican model began to

spread. The idea that the sun goes around the Earth and that the planets go around the Sun was revived by the Danish astronomer Tycho Brahe (1546–1601). Tycho was one of the greatest astronomers of the days before the invention of the telescope. His reputation was made when he published, in 1573, a short book entitled De Nova Stella , which means “On the new star.” In it Tycho described his observations of a new star that had A drawing from Copernicus’s 1543 book, which shows the Sun at the center of the Universe as planets, including the Earth, revolve around it. Like Ptolemy, Copernicus placed a sphere of stars beyond the sphere of Saturn.