Venus, Saturn and Regulus cluster before dawn in October

October 1, 2007

Venus

Venus, Saturn and Regulus will dance a pas de trois low in the eastern sky an hour before sunrise during October, with the crescent moon joining them on Oct 7.

Venus will be the highest it ever gets in the morning sky for watchers at mid-northern latitudes. This dazzling "morning star" will easily outshine its nearby companions.

Saturn will be noticeably dimmer than usual because its rings have now closed to only a few degrees from edgewise for the first time in 10 years.

Regulus, the brightest star in the constellation Leo the Lion, completes this spectacular trio of two planets and a star. The group of three objects will be most compact on Oct. 10. As the month progresses, Venus will gradually drop away toward the horizon as Saturn and Regulus move higher.

In the spirit of Halloween, Mars will be a bright, pumpkin-colored point of light rising in the east-northeast in late evening, appearing earlier each week. The planet will be very high in the south just before the start of morning twilight.

Jupiter will gleam lower and lower in the southwest as the month progresses, sinking into evening twilight. By month's end, the giant planet will set less than an hour after dark.

Mercury will be difficult to find for observers in the Northern Hemisphere, hugging the western horizon right after sunset before disappearing into the afterglow. Mercury will pass between Earth and the sun on Oct. 23.

Light pollution

Does the sky at night seem to have a lot fewer stars than it used to? The stars are still there, but a great deal of energy and money is being wasted on inefficient, improperly directed outdoor lighting. To help demonstrate this problem of light pollution, a project funded by the National Science Foundation is recruiting people to see for themselves the effects of excessive artificial light. For the first two weeks in October, you can participate in a worldwide study to determine just how starry the night now is. For details see http://www.skyandtelescope.com/community/skyblog/observingblog/9875352.html .

Meteor shower

The Orionid meteor shower will peak on the night of Oct. 21-22. The moon will be at first quarter, so if weather permits, observers with a dark sky may see about 20 meteors per hour and perhaps more. The Orionids appear to originate from the familiar constellation Orion the Hunter. Orion will rise before midnight in the east-southeast, and the number of meteors will increase as it gets higher above the horizon. The shower will begin Oct. 2 and end Nov. 7, with meteors gradually increasing from the start and declining after the peak, so skywatchers will see a show each night during the week centered on Oct. 21. The Orionid meteors are dust particles from Halley's Comet, left behind in the comet's orbit.

Moon phases

The moon will be at third quarter on Oct. 3, new on Oct. 11, at first quarter on Oct. 19 and full on Oct. 26.

Source: Indiana University