Minnesota Starwatch for October 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 October 2006

This is Minnesota Starwatch for October 2006. We can't say much about the planets this month, since most of them are temporarily unavailable. For instance, Mars and Venus are now far away on the other side of the sun. Jupiter is bright but sets in the west-southwest soon after sunset. Mercury, the innermost planet, is always hard to spot but appears close to Jupiter in the sky for a few days around October 26th. Saturn rises in the northeast around 2 a.m. Full Moon is on the 6th, New Moon on the 22nd.

During a few nights around October 20th, if the sky is clear and dark you may see more shooting stars than usual. At that time, Earth will be passing through a stream of meteoroids left behind by Halley's comet, and the result is called the "Orionid [Or-igh-oh-nid] meteor shower." The best time to see Orionid meteors is after midnight; they seem to come out of the left side of the constellation Orion. Don't expect a spectacular show, but those nights will probably average about one shooting star every three minutes or so.

This month the northern Milky Way passes straight over Minnesota around 8 p.m., especially the constellation Cygnus, the Swan, which some people call The Northern Cross. Deneb [Denn-ebb], the brightest star in Cygnus, is a monster yellow supergiant star about 1600 light-years away and 70 thousand times as powerful as the Sun. As the Earth turns, every night Deneb passes "exactly" over Forest Lake, about 25 miles northeast of Minneapolis and St. Paul. Then, about 4 minutes later, it passes exactly over the town of Monticello, Minnesota.

The odd thing about this is that a hundred years ago the path was about 20 miles to the south. When Teddy Roosevelt was president, each night Deneb passed over the present site of Woodbury then 40th street in residential Minneapolis, and then over Big Island in Lake Minnetonka. This change has occurred mainly because the Earth's axis is slowly swiveling around in space--astronomers call it precession. Precession is indirectly caused by the Sun and Moon, and takes about 26 thousand years for a full cycle. This may seem a long time, but just one or two years of precession is enough to affect the pointing of big telescopes. A few hundred years ago, Polaris, the North Star, was quite a noticeable distance fromt he real celestial north pole--which gave Columbus some trouble when he was navigating. In fact, Earth's pole will point closest to Polaris around the year 2100. A few thousand years after that, Earth will have a different north star.

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