dipper@utastro.UUCP (02/15/86)
Today is the birthday of an Italian scientist who helped lay the foundation for modern astronomy. More -- after this. February 15 Galileo's Birthday This is the birthday of Galileo Galilei, born four hundred and twenty years ago today. He grew up during a time when people believed that Earth was a place around which the whole universe revolved. This old model maintained that celestial objects moved by some power of their own. Galileo believed in a different idea. He supported the model of Copernicus -- who'd said that the sun, not the Earth, was the center of the universe. While this model had an orderly, aesthetic appeal, it lacked a good physical explanation. Galileo set out to supply the answer. He believed there was an external force that caused the planets to revolve around the sun. And he explored this force by studying the motion of objects on Earth. Galileo is remembered for popularizing the experiment where two falling objects of different mass hit the ground simultaneously. The refracting telescope was greatly improved by Galileo, and the discoveries he made with it fascinated the public. He revealed that the moon had a rough, cratered surface and that the hazy band of the Milky Way was really a mass of stars. He also proved that the sun rotated, and -- most important to him -- that there were small bodies revolving around Jupiter. His discovery of Jupiter's moons did a lot to bolster the theory of Copernicus. It proved bodies do indeed revolve around other bodies in space -- besides the Earth. Galileo's telescopic observations made the Copernican model more believable. And his understanding of motion helped Isaac Newton later apply it to the cosmos -- and eventually explain the force of gravity. Script by Holly Clark. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin