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The Sky This Week, 2010 October 19 - 26

Greeting Winter's Stars

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Jupiter and its inner large moon Io
Imaged from Alexandria, VA on 2010 OCT 18, 01:59 UT 


The Moon brightens the overnight hours this week, with the Full Hunter’s Moon occurring on the 22nd at 9:37 pm Eastern Daylight Time. The Hunter’s Moon shares similar orbital geometry with the Harvest Moon, so it appears to rise at shorter nightly intervals over successive evenings around the time of the full phase. At the latitude of Washington, Luna rises between 25 to 30 minutes later on successive nights around Full Moon; the more "normal" interval is around an hour’s difference. Like the Harvest Moon, whose "extra" light once helped farmers bring in their crops, the Hunter’s Moon allows game-seekers a little extra time to pursue their quarry over the harvested stubble of the now-barren fields. Look for Luna about six degrees above bright Jupiter on the evening of the 19th. On the 24th she is four degrees west of the Pleiades star cluster, and two nights later may be found between the stars that mark the "horns" of Taurus, the Bull.

The nights of waning October are now becoming noticeably longer than the days. We are just barely a month past the autumnal equinox and daylight is rapidly dwindling past 11 hours’ duration. While we are still observing Daylight Time, mornings are definitely darker, and that second cup of coffee is becoming more of a necessity than a luxury! However, the dark of the pre-dawn sky now means that I can visit with some old friends as I go out to collect the morning paper. Looking up to the south in the gathering dawn I can see the bright stars of the Great Winter Circle twinkling down around the majestic figure of Orion. Sirius, the "Dog Star", blazes with a light that is currently second only to the bright planet Jupiter, whose culmination occurs at around the time most of us turn in for the night. Despite the Moon’s bright glare, very clear autumn evenings now reveal the first of the winter stars rising in the east at bed-time, with the knotted clump of the Pleiades leading the way as summer’s constellations beat a hasty retreat in the west.

Faint ruddy Mars can still be found in the southwestern sky in the glow of fading evening twilight. Turn a pair of binoculars this way to locate him as he closes in on his red-tinged rival, the star Antares in the constellation of Scorpius. By the end of the week Mars will be 11 degrees west of Antares but only a few degrees above the southwest horizon at 7:15 pm. You’ll need a high vantage point to watch the two objects converge before they are swallowed up in the Sun’s twilight glare.

Jupiter begins the week in the company of the Moon, but even after Luna’s departure you should have no trouble spotting him. The giant planet is the brightest object in the current night sky after the Moon, and he can be seen to advantage from just after sunset until the wee hours before dawn. I’ve enjoyed some very nice views of him from the front yard over the past week on evenings of still atmospheric conditions, and the detail on his turbulent cloud tops is an ever-changing palette of pastel hues of beige, brown, and red. He will remain well-placed for viewing through the end of the year, so you should have plenty of opportunities to make your own personal discoveries of the constant evolution of this distant, massive world.

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