Minnesota Starwatch for April 2006
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Starwatch Newsletter

Minnesota Starwatch is a newsletter describing the night sky in the Midwest.

It is updated monthly, and is produced by the
Department of Astronomy, University of Minnesota
116 Church Street SE, Minneapolis, MN 55455

Minnesota Starwatch for April 2006

Several planets make good appearances in our April sky this year. Mars and Saturn are high in the west as evening twilight fades. Both will remain above the horizon until midnight or later all month. Ruddy-colored Mars is easy to see after twilight and directly above the readily recognized constellation Orion the Hunter. Saturn, about twice as bright, is higher and a bit to the south of Mars. The crescent moon passes above Mars on April 3rd and over Saturn three days later. Both planets are on the other side of the solar system from us right now. Mars won't be well positioned for close-up views of its surface again until late 2007. Saturn, since it is physically much larger than Mars, does show a nice disk in a small telescope. Its famous rings are tilted nicely right now, so should be relatively easy to spot. Venus and Mercury rise in the southeast before the sun in the early morning. Both remain low to the horizon and in twilight throughout the month, so they are relatively difficult to spot.

During the evening of April 1st the moon will cross in front of the Pleiades star cluster, also known in Greek mythology as the Seven Sisters. Between about 7:00 and 8:00 PM the moon's disk will cover, or occult several bright stars in this nearby cluster of stars. The Pleiades is a group of relatively young stars about 400 light years away all formed about the same time. They span a space of about 12 light years and are kept together by their mutual gravity. They are visible on the shoulder of Taurus the Bull. The Pleiades is so distinctive that it is featured in the mythologies of cultures all over the world. It is mentioned in Chinese writings more than 4000 years old, and in the Bible. The ancient Egyptians named it Chu; in Japan it was Subaru, while the Aztecs called the cluster Tianquiztli. Even far to the south, in New Zealand, the native Mauri noticed these stars, calling them "Mataariki", meaning "small eyes". To modern astronomers clusters of stars like the Pleiades are important tools for understanding how stars are formed and how they evolve over their lives. We understand now that the Pleiades formed about 100 millions years ago, during the age of dinosaurs on Earth, out of a large cloud of dusty hydrogen gas. Some gas and dust residue from that formation is still visible in telescopes as fuzzy wisps. Eventually, after another 250 million years or so, the stars of the Pleiades are expected to be dispersed due to tidal forces as the cluster orbits the Milky Way galaxy. In the meantime, they present us with a striking pattern of bright stars to enjoy.

For fun Astronomy Outreach programs check out our Public Outreach link, or if you're interested in how you can help build the new Minnesota Planetarium, please call 612-630-6151 or visit http://www.mplanetarium.org.

Como Planetarium is offering fun family shows about astronomy on a limited basis; please call 651-293-5398 for more info!

The Minnesota Starwatch is produced by the University of Minnesota Astronomy Department.