The telescope has only been in used in astronomy for about 400 years, but scientists have been accurately recording the movements of stars and planets for at least the last 5,000 years. For hundreds of years it was widely believed that the world was a stationary object at the center of the universe. At first glance from our ground level point of view, that is exactly what it looks like.

     In the sixth century B.C., the Greek mathematician Pythagoras, was the first to propose that the world was a sphere rotating on its own axis. This idea was rejected and derided by his contemporaries who could not imagine a world that was not flat or stationary. Aristotle’s theory became the accepted scientific explanation. He believed that the Sun, Moon and stars were attached to separately rotating spheres made of an invisible substance he called "quintessence."

     A hundred years later, the Greek scholar Aristarchus of Samos put forth a theory that was so revolutionary that it was immediately dismissed as absurd by most of the leading Greek philosophers of the day. He suggested that the Earth orbited the Sun along with the rest of the planets. Lacking any mechanical means to prove his theory, Aristarchus was ignored. He died in 230 B.C.

     No other theories of the Universe were proposed until 400 years later when Claudius Ptolemaeus, known as Ptolemy, came up with an explanation that was accepted by the scientific community. He deduced that the Earth was the supreme body of the Universe, lying stationary at its center. The Sun and the Moon moved around the Earth in circular orbits along with the visible planets--Mercury, Venus, Mars, Jupiter, and Saturn. The wide acceptance of this theory was helped by the fact that the political and religious authorities had joined together in the form of the Holy Roman Catholic Church, which held the power of life or death over its subjects. It tolerated nothing that would disagree with church teachings about the true nature of the world, and its central location in the Universe.

     To explain the fact that the planets do not move in perfect circles, Ptolemy plotted a complicated system of smaller individual circles, or epicycles, which he believed the planets and stars must follow while they were, at the same time, traveling around the central Earth.

     While Ptolemy’s theory seems easy to disprove, it formed the unquestioned basis of astronomy until the 16th Century. Nicolaus Copernicus was born in Poland in 1473. By the time he was 40, after a lifetime of studying astronomy, he was convinced that Ptolemy’s theory was wrong. Copernicus' model of the Universe had the Earth and other planets moving around the Sun in perfect circles.

     Copernicus was reluctant to publish his theories because he knew how the Church would feel about the Earth not being the center of the Universe. Just the mere rumor of his theories prompted the religious reformer Martin Luther to denounce Copernicus as a fool who wanted to turn the science of astronomy upside down. His book, Concerning the Revolutions of the Celestial Bodies was printed in 1542, but the printer added an unauthorized introduction stressing that the book’s theories were not to be taken literally. Perhaps this is why the Catholic Church overlooked this book and did not ban it until 73 years later when Galileo unwittingly drew attention to it. It remained banned by the Church until 1822.

     One truth that eluded Copernicus was the fact that the planets move in elliptical orbits, not circles. Like Aristarchus, Copernicus had no modern technological means to prove his theories. His ideas could not be comprehended by those who had already set their Ptolemaic beliefs in stone.