Minnesota Starwatch for October 2007
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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 2007

Hello, this is Minnesota Starwatch for October 2007. The cool, crisp nights of October make for terrific star watching. As the Milky Way, the broad patch of faint starlight from the disk of our Galaxy, begins to set in the west, the spectacular winter constellations begin to rise in the east. Early in the evening the constellation Cygnus, the Swan, which is also called the Northern Cross, dominates the northern reaches of the Milky Way. The brightest star in Cygnus, Deneb, is a supergiant star about 1600 light-years away. It has the same surface temperature as the sun, but is about 100 thousand times as bright as the Sun because of its huge size. Deneb is about 300 times larger than the 800,000 mile diameter of the sun!

As the night progresses, we see Taurus, the Bull, rising in the east pursued by Orion The Hunter who is followed by his hunting dogs Canis Majoris and Canis Minoris. The hourglass-shaped Orion is the most prominent and recognizable of the winter constellations. The fuzzy patch below the three bright stars across the center of the hourglass that define Orion's belt is Messier 42, one of the most active star formation regions in our Galaxy. M42 is spectacular when viewed through a small telescope or binoculars. You should be able to pick out the four hot young stars of the Trapezium, surrounded by a large greenish gaseous nebula. Three more hot young stars can be seen just to the southeast of the Trapezium. The red giant star Betelgeuse, which defines the northeast corner of the Orion hourglass, is a swelled-up star called a red supergiant. This is a phase that massive stars enter when they exhaust the hydrogen fuel that sustains their interior furnace during most of their lifetime. When Betelgeuse reaches the end of its supergiant phase, sometime within the next few million years, earthlings will be treated to a spectacular sight as it erupts in a supernova explosion. The explosion, caused by the rapid gravitational collapse of the fuel-exhausted core, will cause Betelgeuse to become 10 billion times as luminous as the sun, and even at Earth it will approach the full moon in brightness! Within a year, the shell of ejected material will be big enough to be seen easily with a small telescope, and the explosion will be seen reflected off the nearby Orion dust clouds for many years. Of course, since Betelgeuse is 540 light years away, the explosion will not be seen on earth until the year 2543 even if it were to happen tomorrow!

Get up early between October 20th and 22nd to watch for shooting stars from the Orionid meteor shower. Meteor showers are always best observed after midnight, but this year the waxing moon may interfere somewhat. Nonetheless, observers at dark sites might expect to see peak counts of up to 20 meteors per hour. The shower results from the Earth's passage through the orbit of the famous Comet Halley.

Planet viewers will find Jupiter low in the southwest in the early evening and Mars rising in the east by late night. Before dawn, Mars will have ascended high to the south; Saturn and Venus, the Morning Star, will be rising in the east. New Moon will be on the 11th and Full Moon will occur on the 26th.

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.

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