dipper@utastro.UUCP (Debbie Byrd) (12/25/85)
Comet Halley became world famous on Christmas day, in 1758. We'll talk about it -- after this. December 25 A Comet for Christmas On today's date in the year 1758, the world got a Christmas present from the cosmos. The first comet ever suspected to return, did. Today we know that, like planets, comets orbit the sun. But their orbits carry them first through the deep freeze of space in the outer solar system -- then sizzlingly near our mother star. We only see comets when they come near the sun. Then, they sprout their long tails and appear fleetingly as ghostly visitors to our night sky. Throughout most of recorded history, comets were completely misunderstood. What's more, they were considered bad omens -- a menace to kings and heroes. It wasn't until the 16th century that anyone showed that comets reside in outer space. The Danish nobleman Tycho Brahe proved with careful measurements that comets are at least six times as far away as the moon. Well, they're really much farther away. But no one proved that until Edmond Halley came along. In 1682, at the age of 26, he saw a comet. Twenty-one years later, he plotted its orbit and noticed similarities with the orbits of comets that had appeared in previous years. He boldly suggested these comets were all the same comet -- which we see at intervals of about 76 years, when it's closest to the sun in its orbit. He predicted that the comet of 1682 would return in 1758 -- and on Christmas Day of that year, the comet was discovered again. It was thereafter called Halley's Comet, for the man who discovered that comets are members of the solar system. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin