Minnesota Starwatch

University of Minnesota

Department of Astronomy

Minnesota Starwatch for September 2004
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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 September 2004

Since the moon was full on August 29, this month starts with the moon waning and last quarter moon is on the 6th. This is followed by new moon on the 14th, first quarter moon on the 21st, and a full moon on the 28th. The full moon on the 28th is the closest full moon to the Autumnal equinox on the 22nd, and thus, is the Harvest Moon. For several nights in a row the nearly fully illuminated moon will appear to slowly rise above the eastern horizon at the end of the day. Anyone out working in the fields is sure to appreciate the extra light. The moon will be furthest from the earth (apogee) on the 11th, and closest to the earth (perigee) on the 26th. Although most of the impression of the larger than true angular size of the moon is due to its proximity to the horizon, its position in its orbit means that the moon will actually be close to its maximum angular size for the Harvest Moon.

Early risers have the opportunity to view three bright planets this month. Venus can be observed as the bright object in the east up to four hours before sunrise. On the morning of the 10th you can see the crescent moon about 5 degrees (or 10 moon diameters) from Venus.

Saturn is very close to Venus, and, in fact, starts the month just 2 degrees higher in the sky. As the month proceeds, Venus moves closer to the sun, rising later, and increasing the separation from Saturn. Venus is always the brighter of the two, but Saturn will be brighter than any stars except Sirius and Vega.

For those of you who have never seen Mercury, this may be the month. Mercury brightens rapidly during the course of the month, as it becomes more fully illuminated. On September 9th, Mercury reaches its greatest elongation, or angular separation from the sun, and will be most easily observed in the eastern sky rising about one hour before the sun. Unfortunately, this means that it is also moving closer to the sun for the rest of the month as it moves behind it. On the morning of the 11th, Mercury, and the bright blue star Regulus appear closer together than the diameter of the moon. Mercury viewing will be over by mid-month as it approaches too close to the sun, but Regulus will remain on the eastern horizon at sunrise.

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!

This has been a Minnesota Starwatch produced by the University of Minnesota Astronomy Department.