History is a kind of introduction to more interesting people than we can possibly meet in our restricted lives; let us not neglect the opportunity. ~Dexter Perkins

Near the end of the 16th century, a man named Galileo was born in Italy. In his early career he taught math at a university, the beginnings of his fame. Galileo the math teacher made his first step into Galileo Galilei astronomy when he demonstrated to his students that Aristotle was wrong about object of different weights falling at different speeds. He lost his position for this perceived insult of a respected great, so he moved on to the University of Padua. It was there that his ideas about astronomy truly began.

In Padua, Galileo invented the compass and began studying physics. He discovered the law of falling bodies and the parabolic path of projectiles. These two ideas were key to astronomy as it progressed. But at the time Galileo claimed to have no interest in the subject other than that he believed the work of Copernicus rather than that of Aristotle and Ptolemy. Copernicus' theory was of a heliocentric solar system in which the planets circle the sun. However most people held that Aristotle and Ptolemy were correct in their theory that all the planets, even the sun, orbited the Earth. Of course today we know that Ptolemy and Aristotle were wrong.

Galileo was the first to look at the night sky through a spyglass, thus using the first telescope. He used it to see features on the moon such as mountains and craters. Galileo also determined that individual stars made up what was called the Milky Way. He went on to discover Jupiter's four largest moons. After publishing this information, he was named the royal mathematician in the court at Florence. Now he could devote full time to his studies. Nine months later he showed that Saturn had phases. This was another nail in the coffin for Ptolemy's and Aristotle's ideas about the solar system.

Galileo's original dispute was with Aristotle's teachings. Because so many agreed with Galileo his theories were widely published. But because Aristotle's work elevated man to key position in all the universe, the church supported his work. In 1614 a priest in Florence denounced Galileo Galilei Astronomy. Galileo responded by writing a letter proclaiming the bible irrelevant to science. In 1616 the church censored Galileo's books, and a cardinal instructed him to stop teaching that the Earth moves. Galileo complied, continuing his study of falling objects, comets, and methods to determine longitude at sea based on the phases of Jupiter's moons. Galileo signed a document proclaiming his agreement with the Earth centered solar system, one in which the Earth doesn't move. But he had one more thing to say on the subject. "I would say here something that was heard from an ecclesiastic of the most eminent degree; "And yet ... it moves."