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 August, 2002.

Venus will be visible down close to the western horizon right after sunset this month. In this position, the light from Venus will travel through much more of the Earth's thick atmosphere than is the case for stars and planets viewed more overhead. Variations and turbulence in the Earth's atmosphere will often cause the image of Venus to change color, appear to bounce around, and become distorted. Try and locate Venus just after sunset and keep your eye on the planet. See if it behaves strangely, but don't report any UFO sightings!

After following Venus for a while, raise your eyes directly upward about half way up. You should see the bright star Arcturus. Arcturus is the brightest star in the constellation Bootes, a constellation that is first mentioned in Homer's Odyssey. The name for this constellation must date back at least 3000 years, and probably further. The original Greek name for Bootes may have referred to the shouts of either a driver of oxen or hunting dogs in pursuit of a bear, the nearby constellation Ursa Major. Ursa Major, or Great Bear, is best known as the Big Dipper and lies to the right (northwest) of Bootes after sunset. Arcturus, the third brightest star in the northern hemisphere, has been an object of interest to Western people for thousands of years. In fact, it may be one of the first stars given a name, which in ancient Greek meant watcher (or guardian) of the bears. Arcturus, slightly orange in tint, is a relatively warm red giant. This means it is only a bit cooler than our Sun, but much larger in size and hence much more luminous. Arcturus is about 25 times the size of the Sun and 100 times more luminous. It appears so bright in the sky not just because it is an intrinsically bright star, but also because it is a relatively close 34 light years away. To put this in perspective, consider Betelgeuse, the red supergiant in Orion. Betelgeuse is over 1500 light years away, but almost as bright in the sky as Arcturus. Betelgeuse can appear so bright even though it is so far away because it is an amazing 60,000 times brighter than our Sun. Betelgeuse is so large, in fact, that if it were placed at the center of our solar system, it would stretch past the orbit of Mars.

The Minneapolis Planetarium offers a wide variety of programs for all ages. For more information, call 612/630-6150.

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

Minnesota Starwatch is available on-line at http://www.astro.umn.edu/Outreach/pub_out.html

This has been Minnesota Starwatch, produced by the University of Minnesota Astronomy Department in cooperation with WCCO Weather Center.

Last Updated: Wed Jul 17 16:15:06 2002