Minnesota Starwatch for March 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 March 2007

Hello, this is Minnesota Starwatch for March 2007. The western sky early in the evening is still dominated by the spectacular, rich constellations of Winter. Most prominent among these is the hourglass-shaped constellation of Orion, the Great Hunter. As he has for aeons, Orion pursues his prey, Taurus the Bull, who is fleeing westward. Three bright stars across the center of the hourglass define Orion's belt. At the tip of the sword that hangs from the belt is Messier 42, one of the most active star forming regions in our Galaxy. M42, popularly called the Orion Nebula, 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. You can view a remarkable three dimensional visualization of the Trapezium and the surrounding nebula at http://vis.sdsc.edu/research/orion.html. This visualization was produced by a collaboration of scientists at the San Diego Supercomputer Center and the American Museum of Natural History Hayden Planetarium.

Another young stellar cluster with seven bright members, the Pleiades (The Seven Sisters), will be high in the western sky just after sunset. This young open star cluster is another excellent viewing target for binoculars or a small telescope. Meanwhile, the NASA Spitzer Space Telescope (http://www.spitzer.caltech.edu/. ), an infrared observatory that was launched on August 25, 2003, continues to return stunning images of stellar nurseries that are similar to the Pleiades and M42. The most recently acquired example is the study of the giant star-forming cloud of gas and dust called the Eagle Nebula. (See http://www.spitzer.caltech.edu/Media/releases/ssc2007-01/index.shtml). The Eagle Nebula is located 7,000 light-years away in the constellation Serpentis which will just be peeking above the horizon in the southeast at sunrise by the end of the month. The new Spitzer images show evidence that a supernova explosion of a massive star about 6,000 years ago might have destroyed the Eagle. This means that Earth-bound astronomers will have to wait until the year 3007 to witness its destruction.

Betelgeuse, the reddish star that defines the northeast corner of the Orion hourglass, is a swelled-up star called a red supergiant, similar to the star that may have exploded in the Eagle Nebula. This is a phase that massive stars enter when they exhaust the hydrogen fuel that sustains their heat 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 ejected shell 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 2547 even if it were to happen tomorrow!

The big event of the month will be the first total eclipse of the moon in more than two years. In the United States, totality will occur just as the moon is rising on Saturday, March 3rd. If you can travel to Boston, you will be able to see almost the entirety of the total eclipse. Alas, in Minneapolis, totality ends two minutes before the 6 PM moonrise. Twin Cities residents will, however, get to watch the waning partial eclipse until 7:12 PM. Note that the Earth’s shadow on the face of the moon is curved, a fact that ancient astronomers took as evidence that the Earth was round and not flat.

All of the five bright classical planets can be viewed during March. Mercury will pull out to its maximum western elongation of 28 degrees from the sun on March 22nd. This is about as good as Mercury viewing ever gets. Venus will rise ever higher in the sky as a bright evening star. Saturn will be in the east-southeast at nightfall, and Jupiter will rise around midnight. Mars, the “red planet”, can be seen rising in the southeast at dawn.

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.