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The Sky This Week, 2011 November 29 - December 6

An ascending Moon and bright planets for dark nights.
Jupiter & Callisto, imaged on 2011 NOV 25, 02:21 UT

The Moon brightens the evening sky this week, climbing steadily through the dim autumnal constellations to join bright Jupiter by the week’s end. First Quarter occurs on December 2nd at 4:52 am Eastern Standard Time. Look for Luna high above the lonely star Fomalhaut on the evening of the 2nd. On the evening of the 6th Luna is only five degrees northeast of bright Jupiter.

Even though the winter solstice is still several weeks away, I have always associated the beginning of winter with December 1st, which is when meteorologists shift over to their winter climate models. Early December is when the year’s earliest sunsets occur here in the Northern Hemisphere, and for the next month we’ll seem to experience the full darkness of long winter nights. This effect is accentuated by the constellations that are present in the early evening sky. With a handful of exceptions there are hardly any stars brighter than third magnitude among the asterisms that cross the meridian until the late evening hours. Fortunately this week we have the waxing Moon to brighten the scene for us until the stars of the Great Winter Circle approach center stage by the midnight hour. This is a great time to get acquainted with the Moon as she passes through the relatively empty autumnal sky. Whether you’re looking at her silvery face with binoculars or an observatory-class instrument, there is always something to see on her craggy face. Pay particular attention to the so-called "terminator", the line dividing the sunlit lunar hemisphere from the dark. It is here that the low angle of sunlight exaggerates the shadows of lunar mountains and craters and gives some impression of what a rugged, inhospitable environment the Moon is. Next week marks the 39th anniversary of the flight of Apollo 17, our last human visit to our only natural satellite.

You may have noticed the thin crescent Moon near the dazzling glow of Venus over the recent holiday weekend. Venus is now climbing rapidly from her southerly perch along the Ecliptic and is quickly gaining altitude on the Sun. Venus now sets after the end of evening twilight, so you should have no trouble spotting her as soon as the Sun goes down. By the end of the year she will be well-placed in the southwest sky and visible against a fully dark background.

Giant Jupiter continues to dominate the evening sky. Old Jove is in prime viewing position high in the east beginning at the end of evening twilight. By 10:00 pm he’s on the meridian and commands attention until well into the morning hours. After the Moon, Jupiter is probably the most rewarding solar system object to view with a small telescope. Almost any modern small ‘scope will far outperform the primitive glass that Galileo first turned toward Jupiter back in the winter of 1609 – 1610. About all that he could discern was a bright dot flanked by four little "stars" that moved in position from night to night. Today an instrument of comparable magnification, about 30X, should reveal the two great equatorial cloud belts on the planet’s surface as well as Galileo’s four bright moons.

Early risers can catch the red planet Mars near the meridian as morning twilight begins to gather. Mars is gearing up for opposition this spring, and if you have a moderate-aperture telescope you should start observing him now. His ruddy disc is now about half the size it will subtend this spring, and some details, such as his north polar ice cap, should be visible in moments of steady air. The Mars Curiosity Rover successfully launched toward the planet last week; on August 6th it will hopefully plant a vehicle the size of a small car onto the planet’s distant rusty soil.

The planet Saturn is also visible in the brightening light of dawn. Look for his golden glow just above the blue tint of the bright star Spica. Saturn will get his turn in the spotlight by late spring next year, something I always look forward to.

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