dipper@utastro.UUCP (Debbie Byrd) (01/07/85)
This is the anniversary of the discovery of the first evidence that Earth isn't the center of EVERYTHING. More -- after this. January 7 Discovering Jupiter's Moons The earliest humanoids in prehistoric times were well aware of the bright light of the moon. And yet the concept of MOONS -- of worlds orbiting other worlds besides Earth -- was not taken seriously until the seventeenth century. It was on January 7, in the year 1610, that Galileo first used his crude telescope to discover three of the four largest moons of Jupiter -- now called the Galilean satellites. Each night they appeared as pinpoints strung out on either side of the planet -- a striking arrangement against the random stars. But what was more remarkable was the fact that these small lights clearly orbited Jupiter -- actually swung around it in space -- and so could be seen to change positions from one night to the next. Since Jupiter's satellites are essentially invisible to the naked eye, Galileo's discovery was only made possible by the invention of the telescope. Before it, no celestial body had ever been recognized to orbit any other world besides the Earth. In Galileo's time, the moon, sun, planets and stars all were thought to orbit our world. The powerful western church taught that these celestial objects belong strictly to the realm of heaven -- where nothing ever changed. Galileo's telescope was one of the first ever to be built. He used it to observe craters on the moon and spots on the sun -- amd the four worlds orbiting Jupiter. He was the first to see evidence that the heavenly realm is actually a part of nature -- alien and yet similar to the familiar natural world around us here on Earth. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin