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The Sky This Week, 2012 January 10 - 17

Dazzling Venus in the evening, a grand conjunction before dawn.
Moon_120107_01small.jpg

Lunar Terminator, 2012 January 7
Imaged from Alexandria, VA with a 20-cm (8-inch) telescope
and a Canon EOS Rebel T2i DSLR camera


The Moon wanes in the morning sky this week, drifting through the rising stars of the springtime sky as she wends her way toward Last Quarter, which occurs on the 16th at 4:08 am Eastern Standard Time. Look for Luna about six degrees southwest of the bright star Regulus in the constellation Leo rising in the east in the late evening on the 11th. On the 13th she passes well south of ruddy Mars. If you’re up before dawn on the 16th, the moon forms an attractive tight triangle with the star Spica in Virgo and the golden-hued planet Saturn.

The final days of our latest sunrises pass early in the week. Old Sol gradually begins to rise earlier beginning on the morning of the 13th. He’s picking up the pace at sunset, though, steadily setting about a minute later each night. By the month’s end he’ll be setting close to 5:30 pm here in Washington.

As the Moon drifts into the morning sky the stars of the Great Winter Circle return to prominence in the evening hours. We’ve had a few chilly nights to remind us that winter is not over yet, and the bright glimmer of these colorful stars still seems to add a small amount of light and warmth to these long nights. On particularly crisp and cold nights these stars and their associated constellations remind even city dwellers of the interesting and storied characters traced out in ancient skylore. This is prime time to spot Orion, the Hunter, which is probably the most prominent constellation in the entire sky. Visible from every inhabited part of the planet, Orion has figured prominently in the mythology of nearly every culture that has come and gone over the millennia. His principal stars, all first- or second-magnitude, are easy to spot from even the most light-polluted locations, and only a small application of imagination turns them into a human-figured outline. Orion is on the meridian by 10:00 pm this week, so give him a look before you retire for the evening.

Venus continues her climb to prominence in the early evening sky. You cannot mistake her for any other object between sunset and 8:00 pm. She is currently passing through the relatively dim stars of the setting autumnal constellations, so there is nothing to match her brilliant glow during the twilight and early evening hours.

Jupiter now straddles the meridian at the end of evening twilight. Old Jove still dominates the evening sky once Venus nears the horizon, but he’s gradually yielding to his more comely rival. He’s still a great target for perusal in the small telescope. On the evening of the 13th you can watch the shadow of the giant planet’s innermost large moon Io cross the planet’s cloud tops between 7:31 and 9:41 pm EST. Io itself emerges from transiting the planet’s disc at 8:22 pm. Events such as these provide a great example of the dynamic forces at work in the solar system, and you can watch them happen in "real time".

Ruddy Mars comes up with the Moon late on the evening of the 13th. By midnight the red planet is high enough to train the telescope upon, and while his apparent disc is only about 1/4th the size of Jupiter’s there’s still detail to be seen. The planet’s brilliant north polar ice cap will probably be his most prominent feature, but you may be able to discern some of his darker patches against the bright pink of his vast deserts.

Saturn is still best seen just before sunrise. The ringed planet is located only a few degrees east of the blue-tinted star Spica, lead star in the sprawling constellation of Virgo. The last quarter Moon will join planet and star for a lovely conjunction as dawn gathers on the 16th.

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