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The Sky This Week, 2011 January 4 - 11

Happy New Year!
Last_Sunset_2010small.jpg

Last Sunset of 2010, 31 December, 16:57 EST
Imaged from Morattico, Virginia with a Canon PowerShot S2IS
digital camera, 1/500s @ f/5.6, ISO 50


The New Year starts off with a New Moon, which occurs on the 4th at 4:03 am Eastern Standard Time. At this time the disc of the Moon partially obscures that of the Sun as seen from most of central and eastern Europe, parts of north Africa, and the Middle East. At its greatest extent, visible at sunrise in southern Sweden and Finland, some 85% of Old Sol will be obscured by the Moon. This is the first of four partial solar eclipses that will take place in 2011. There will also be two total eclipses of the Moon this year, but none of these events will be visible from the eastern United States. Once the Moon has slipped past the Sun, we should see the waxing crescent in twilight on the evening of the 5th. By the 9th and the 10th Luna will be climbing higher in the sky and sliding past bright Jupiter to brighten our long winter nights.

Attentive skywatchers have probably noticed by now that the time of sunset here in the Washington area is now some 15 minutes later than it was in early December. This week the time of sunset occurs after 5:00 pm for the first time since November 8th. Yes, the days are gradually getting longer, but if you’re an early riser the latest sunrise won’t occur until January 5th, when the Sun peeks over the horizon at 7:27 am EST. By early next week we’ll begin to see the turnaround in sunrise time, though, and we’ll really begin to notice the lengthening days.

This week also marks another milestone in our annual journey around the Sun. On January 3rd we reached perihelion, Earth’s closest point to Old Sol for the year. Our day-star’s center was a mere 147.1 million kilometers (91.4 million miles) from the center of Earth. This means that we are moving at our most rapid orbital velocity around Old Sol, which also means that winter is thus our shortest season in the Northern Hemisphere! Take heart, summer lovers.

The early evening sky still finds Jupiter in a prominent position as twilight gives way to darkness. The giant planet still shines down from the south and southwestern sky in evening twilight and the first hours of the night. There’s still time to catch good glimpses of him through the telescope, although the best time to see him is during the dinner hour. Over the course of the past couple of weeks I have found myself leaving the table to snap a few images of his resurgent South Equatorial Belt while Jupiter was favorably placed in the sky. Time is running out on him, though, as the Sun is relentlessly catching up to him. Every night he sets 3 to 4 minutes earlier, and by the month’s end he’ll dip below the western horizon at 9:30 pm.

As Jupiter prepares to exit the evening sky, the planet Saturn prepares to take his place. Currently the ringed planet rises at around 12:30 am, but by the month’s end he crests the southeastern horizon some two hours earlier. Saturn is definitely worth getting up for in the morning, though, since a huge storm has erupted in the planet’s northern hemisphere clouds that’s visible with modest telescopes. At 6:00 am the planet is high in the south and well-placed for viewing before breakfast.

Bright Venus still dominates the view to the southeast as morning twilight gathers. She reaches her greatest elongation west of the Sun on the 8th, then begins a very gradual descent toward the horizon that will ultimately carry her behind the Sun in mid-August.

The elusive planet Mercury reaches elongation a day later as he undergoes one of his better morning apparitions for the year. His amber glow may be found about 10 degrees above the horizon 45 minutes before sunrise. If you have a pair of binoculars try to spot the ruddy star Antares a bit over 10 degrees to the right of Mercury during the early part of the week.

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