Yet It Moves
Today is "Presidents Day" in the US, a holiday for NASA employees. Abraham Lincoln was born February 12 and George Washington February 22. More important for science, February 16 is Galileo Galilei's birthday! 2009 is International Year of Astronomy because 400 years ago Galileo first demonstrated his telescope. This replica is on display at the Griffith Observatory. The telescope offered clues that Earth was not centre of the Universe.
Just as they claim today about the speed of light, scientists of Galileo's time insisted that Earth was fixed. To explain retrograde motion they invoked epicycles, wheels within wheels. (Read: "dark energy") The mathematics of epicycles were highly complicated, which kept most people from understanding astronomy and insured scientists their place in society. If someone claimed that Earth circled the Sun, they could claim that this conflicted with epicycle math.
Galileo did not start his career believing that Earth circles the Sun. When a foreign scholar visited Italy to talk on Copernican Theory, Galileo missed the lectures. Only later did Galileo realise that Copernicus might be on to something. He realised that while believers in Ptolemy had converted to Copernicus, not a single believer in the Copernican system had converted back to Ptolemy. Logically Galileo chose to join the converted.
Galileo's telescope showed phases of Venus, Rings of Saturn, and moons circling Jupiter. These were all indicators that Earth was not centre of everything. Some chose to completely ignore the evidence before their eyes, claiming it was some trick of the telescope. The discovery of double stars was seen as a fault in the telescope!
Galileo gained many detractors. Since Newton's Laws of gravitation had not yet been formulated, detractors would claim that Galileo lacked any mechanism for holding the planets in orbit. Galileo's detractors could also claim the Moon as evidence--if the Moon revolves around us, so should everything else. The learned can be the most resistant to change. Today we know who was right, and 445 years after his birth Galileo is an example for today's scientist.