Starwatch Newsletter Minnesota Starwatch is a tape-recorded message describing the night sky in the Midwest, which can be called by telelphone number (612) 624-2001 It is updated montly, and is produced by the Department of Astronomy, University of Minnesota 116 Church Street SE, Minneapolis, MN 55455

Hello, this is Minnesota Starwatch for February 2003.

This is a fairly routine time for the Moon and Planets. New Moon is on the first day of the month at 4:48 a.m. central time and the moon is Full at 5:51 p.m. on the 16th. Venus is the bright morning star, low in the southeast around 6 a.m.

Venus is now rushing away from us and will curve around toward the far side of the Sun between now and summer. You can also see Mars before sunrise, a little to the right of Venus, but it's not very close to us right now, so it isn't spectacular. Jupiter, on the other hand, is visible all night, it's at "opposition" on February 9. That means that Earth is exactly between the Sun and Jupiter on that date, our annual closest approach to that giant planet.

As for Saturn, it's in Taurus, seeming to hover above the head of Orion the Hunter all month. By the way, that planet now appears close to the Crab Nebula, site of a famous supernova explosion in the year 1054. We can't see the Crab Nebula without a telescope, but it's about 2 degrees to the left of Saturn - about 4 times the angular width of the Moon. Of course there's a wee difference in their distances from us: The Crab is more than 5000 lightyears away but Saturn is only about 70 light-minutes away from us this month - a factor of about 40 million between the two. That's the same as the ratio between the size of a dime and the size of Minnesota.

Since Jupiter is our brightest midnight star right now, this is a good time to remember a famous argument about that planet 400 years ago. In those days - around the year 1600 - scholars were arguing about whether Copernicus had been right in claiming the Earth goes around the Sun. Today we usually forget that the old geocentric theory, with everything going around Earth, had some logical points in its favor. One of them was this: In the ancient picture of the universe, everything in the sky simply revolved around the Earth, period. Sun, Moon, planets and stars all did. In Copernicus' new-fangled theory, of course, Earth was a planet circling the Sun like the other planets. But Copernicus had to allow a glaring exception: The Moon obviously does go around the Earth! In any theory of physics or the cosmos, an isolated exception like that is an embarrassment, a logical disadvantage.

Well, around 1607 Galileo used his telescope and saw that Jupiter has four obvious moons going around it! This was OK for the Copernican theory - now astronomers could just say that planets in general have moons, so Earth's moon isn't an exception after all. But the same discovery was devastating for the ancient geocentric philosophy: If we can clearly WATCH something circling a planet other than Earth, four moons going around Jupiter, for instance, then the Earth obviously can't be the center of all motion.

Galileo also saw something about Venus that totally clinched the argument, but we don't have time to describe that here. The most interesting thing is that the old fashioned philosophers and astronomers were slow to concede. Even though they had no real answer to Galileo's arguments, most of them continued to believe in central Earth for decades. Our modern view of the universe didn't become fully established until the entire generation of older geocentric minded astronomers had passed from the scene.

Friday night telescope viewing begins at 8:00 pm. Please call 612/626-0034 for more information.

For those interested in the Minnesota Astronomical Society, call 651/649-4861 for information their upcoming events.

Minnesota Starwatch is available on-line at http://www.astro.umn.edu/Outreach/pub_out.html. For fun Astronomy Outreach programs or how you can help build the new Minnesota Planetarium, please call 612.630.6151 or visit http://www.mplanetarium.org.

Also, shows are now playing publicly at the Como Planetarium on a limited basis, please call 651- 293-5398 for more info! This has been Minnesota Starwatch, produced by the University of Minnesota Astronomy Department in cooperation with WCCO Weather Center.

Last Updated: Fri Jan 17 10:57:05 2003