dipper@utastro.UUCP (Debbie Byrd) (12/21/84)
Today marks the December solstice -- and also the peak night of a meteor shower. More on both events -- when we come back. December 21: Meteors for the Solstice If you've been watching the western horizon at sunset, you've seen the sun go down a little farther to the south each evening. But that southward trek ends this evening --because today is the December solstice -- which marks the shortest day of the year for the northern hemisphere. The solstice occurs because Earth tilts on its axis. Today, the south pole of the Earth points as much as it can toward the sun. At the south pole around now, the sun never sets at all -- and in the southern hemisphere, people are enjoying long, leisurely days of summer -- and no doubt celebrations of the summer solstice. The winter solstice isn't as much fun to celebrate, unless you count the fact that Christmas always comes soon after it. But this solstice does have something to offer stargazers -- a meteor shower that's generally neglected in the midst of the cold Christmas season. The Ursid meteor shower peaks tonight. It's not an outrageously strong shower -- but the Ursids have had a few good years recently -- and more observations are needed. You might see a meteor every five minutes or so. These bright streaks of light are really debris strewn around in the orbit of Comet Tuttle -- which crash through Earth's atmosphere, and vaporize as they fall -- to leave the bright streak of light some people call a "shooting star." The Ursid meteor shower will be at its peak around midnight tonight. Just remember, to see any meteors, you've got to observe in a dark country sky. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin
wmartin@brl-tgr.ARPA (Will Martin ) (12/21/84)
The local (St. Louis) National Weather Service broadcast this morning said that "Winter starts at 10:23 AM today" (that's CST). Is that precise moment the instant the Earth is closest to the Sun? (The perihelion of its orbit?) Or does that moment refer to something else, and, if so, what? Will Martin USENET: seismo!brl-bmd!wmartin or ARPA/MILNET: wmartin@almsa-1.ARPA
bill@utastro.UUCP (William H. Jefferys) (12/21/84)
>The local (St. Louis) National Weather Service broadcast this morning >said that "Winter starts at 10:23 AM today" (that's CST). Is that precise >moment the instant the Earth is closest to the Sun? (The perihelion >of its orbit?) Or does that moment refer to something else, and, if so, what? Perihelion always occurs around January 3-4. The event that happens today is the winter Solstice, which means that the Sun's declination (the stellar equivalent of latitude) is most southerly. This means in turn that the daytime today is the shortest of the year (and the longest for those basking on the beaches of Rio...) -- "When evolution is outlawed, only outlaws will evolve" Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (USnail) {allegra,ihnp4}!{ut-sally,noao}!utastro!bill (uucp) bill%utastro.UTEXAS@ut-sally.ARPA (ARPANET)