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The Sky This Week, 2010 November 30 - December 7

Mercury at elongation, earliest sunset, and a great morning "photo-op".
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 Jupiter, with SEB Outbreak Plume & Callisto
2010 NOV 29, 01:29 UT


The Moon is a waning crescent in the pre-dawn sky during the first half of the week. New Moon occurs on December 5th at 12:36 pm Eastern Standard Time. Look for Luna’s slimming arc 8 degrees south of golden Saturn on the morning of the 1st. The following morning you’ll have a great photo opportunity as the Moon, dazzling Venus, and the bright star Spica form an attractive triangle some six degrees on each side in the gathering twilight.

With Thanksgiving behind us the year enters its last full calendar month. Meteorologists consider the beginning of winter to be December 1st, while to astronomers the season begins with the solstice on the 21st. Whatever the case, we are now approaching the time of the year’s longest nights. Indeed, the year’s earliest sunset occurs on December 7th, when here in Washington Old Sol dips below the horizon at 4:46 pm EST. By the time of the solstice the Sun will be setting about five minutes earlier, but what we appear to give back is taken away from us by the regression in sunrise times. With the latest sunrise falling some two weeks after the solstice, we find that the year’s shortest day will fall on the solstice itself, when we experience only 9 hours and 36 minutes of the Sun’s wintry light.

Fortunately the year’s longest nights are also dominated by the year’s brightest star display as the beacons of the Great Winter Circle beam down on us from the midnight sky. Nine of the 25 brightest stars may be found surrounding the majestic figure of Orion, the Hunter, as he strides from east to west across the frosty landscape. Somehow the lit decorations that are put up as part of the holiday season pale in comparison to these natural luminaries.

The evening twilight sky becomes the place to look at the end of the week as the newly-waxing crescent Moon passes near the fleet planet Mercury. The elusive planet reaches greatest elongation east of the Sun on December 1st, about seven degrees above the horizon at around 5:15 pm. By the week’s end he’ll be about 10 degrees up, and about six degrees below the nascent Moon.

Giant Jupiter crosses the meridian in the early evening hours, shortly after the end of evening twilight. There’s no mistaking Old Jove in the sky as he shines down with a bright cream-white light from his perch among the dim autumnal constellations. Even though he is well past opposition, Jupiter is still the best target for the small telescope during the evening hours. In addition to the ever-changing configuration of his bright Galilean moons, owners of four-inch or larger telescopes can watch the progress of what appears to be the resurgence of the planet’s once-prominent South Equatorial Belt. A dark plume of material has been emerging from four small spots in the belt’s former location and now trail over 100 degrees of longitude around the planet!

If you get up before dawn over the next several days you’ll have a great opportunity to spy the trio of Saturn, Spica, and Venus joined by the waning crescent Moon. The best morning to view is during deep twilight on the 2nd, when the Moon, Venus, and Spica form a beautiful triangle with Saturn hovering several degrees above. Hope for clear skies as it should be quite a show.

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