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01 Oct 2013

October Astronomy: Let the Moon Be Your Guide to the Stars This Month

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October Astronomy: Let the Moon Be Your Guide to the Stars This Month Robert D. Miller

Follow the moon each day at dusk or dawn—and within one cycle, it will introduce you to as many as all five naked-eye planets, and the five bright stars of first magnitude within the belt of zodiac constellations.

The new moon occurs on Friday, Oct. 4. Two days later, on Sunday evening, Oct. 6, about 20 minutes after sunset, a thin sliver of a young lunar crescent will appear very low in the west-southwest, 20 degrees to the lower right of the bright “evening star,” Venus.

Valley residents would need to seek out a place with an unobstructed sight line in that direction, since the moon will be less than 6 degrees up at 7 p.m., within a half-hour after sunset. (In other words, if you’re in downtown Palm Springs or elsewhere near the mountains, you’re out of luck!) But the view through binoculars is worthwhile: Flanking the moon will be Saturn, 3 degrees to the upper right, and Mercury, 2 degrees to moon’s lower left—all within a 5-degree field!

Mercury and Saturn are in the process of departing the evening sky, but Venus remains visible at dusk until early January.

As the moon withdraws farther from the sun nightly, the crescent thickens, and appears within 8 degrees of Venus the next two evenings—to the planet’s lower right on Monday, Oct. 7, and to its upper left on Tuesday, Oct. 8.

On Saturday, Oct. 12, the local Astronomical Society of the Desert will resume hosting its free monthly star parties at the Visitor Center of the Santa Rosa and San Jacinto Mountains National Monument (on Highway 74, 4 miles south of Highway 111 in Palm Desert). For more info and a map, visit the society’s website, at www.astrorx.org. Early that evening, and until Sunday, Oct. 20, the famous red supergiant star Antares will appear within 5 degrees of Venus. On Wednesday, Oct. 16, they’ll be as close as 1.5 degrees, with Venus passing above the distant star.

High in the east these mornings, another striking pair, of reddish Mars and blue-white Regulus, takes place. From Oct. 7-23, they’ll appear within 5 degrees, and within 1 degree on Tuesday, Oct. 15.

Continue watching the moon in the evening sky until it reaches full on Friday, Oct. 18, when it rises around sunset, and for a few nights beyond, as it rises later each evening.

Look around 6 a.m. (about an hour before sunrise) for these events: On Oct. 22, the moon is near Aldebaran, eye of Taurus; on Oct. 25 and 26, the moon is near Jupiter (the brightest “morning star”) and the Gemini twins, Pollux and Castor. On Oct. 29, find the moon near Regulus and Mars, forming a nearly equilateral triangle 7 to 8 degrees on a side. On Nov. 1, look for Spica 9 degrees to the lower left of the crescent moon. On Nov. 2, about 45 minutes before sunrise, watch for the last thin old crescent moon rising 4 to 5 degrees to the lower left of Spica.

Beginning in mid-November, four bright planets will span the morning sky, and the long-awaited Comet ISON may perform. Check the Sky Calendar website for updates.

More here next month!

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing skywatching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in Planetarium Science and later astronomy and computer science at Michigan State University, and remains active in research and public outreach in astronomy.

Courtesy www.pa.msu.edu/abrams/skycalendar

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