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The Night Sky of December

Dr. Wayne Wooten
Professor of Astronomy
Escambia Amateur Astronomers' Association


For December, the Moon will be in a striking trio with brighter Venus below it and fainter Jupiter to the left of the crescent moon as the month begins. All should fit nicely in a binocular field in twilight on December 1st. By the 2nd, the Moon lies 12 degrees farther east, and Venus is also pulling away from Jupiter, which will be disappearing behind the Sun early next year. The first two weeks of December will thus find the Moon waxing and rising later each day. First quarter moon sits high in the sky and half-lit at sunset on December 5th. The full moon on December 12th will look especially large, since it is close to perigee, as close to Earth as it ever gets. The winter solstice occurs at 6:04 AM CST on December 21, 2008; this is the shortest day of the year. The last two weeks of December finds the moon waning in the morning sky, passing 2.5 degrees south of Saturn on December 19th; both rise about 11 PM due east. New moon is on December 27th. The very slender waxing crescent moon passes just above an evening pairing of Jupiter and Mercury on December 29th low in the SW, and on New Year’s Eve, the crescent moon again passes just north of Venus.

While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere skies, about Halloween visit the website and download the map for December 2008; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. Also available as the next month begins is wonderful video exploring the December 2008 sky, featuring many different objects, available from the Hubble Space Telescope website

Venus dominates the evening sky; telescopically she appears as a small, gibbous disk. She is still on the far side of her orbit. Covered with sulfuric acid clouds, her bright disk reveals no visible details in the scopes. Mercury joins Jupiter at year’s end, passing 1.3 degrees south of Jupiter at hour after sunset on December 31st. Saturn rises in Leo about 11 PM, but if you use a scope to look for the rings, you find them very thin, almost edge on. They will open up slightly, but close again in later August 2009, but by then Saturn is close to the Sun and harder to see.

The square of Pegasus dominates the western sky. The constellation Cassiopeia makes a striking W in the NW. She contains many nice star clusters for binocular users in her outer arm of our Milky Way, extending to the NE now. Her daughter, Andromeda, starts with the NE corner star of Pegasus’‘ Square, and goes NE with two more bright stars in a row. It is from the middle star, beta Andromeda, that we proceed about a quarter the way to the top star in the W of Cassiopeia, and look for a faint blur with the naked eye. M-31, the Andromeda Galaxy, is the most distant object visible with the naked eye, lying about 2.5 million light years distant. To the northeast, Andromeda’s hero, Perseus, rises. Between him and Cassiopeia is the fine Double Cluster, faintly visible with the naked eye and two fine binocular objects in the same field. Perseus contains the famed eclipsing binary star Algol, where the Arabs imagined the eye of the gorgon Medusa would lie. It fades to a third its normal brightness for six out of every 70 hours, as a larger but cooler orange giant covers about 80% of the smaller but hotter and thus brighter companion as seen from Earth. Check it out on a clear December evening, and see it the gorgon is winking at you. If so, then instead of being as bright as Polaris, Algol fade to be only as bright as kappa Persei, the star just to its south. Look at Perseus’ feet for the famed Pleiades cluster to rise, a sure sign of bright winter stars to come; they lie about 400 light years distant, and over 250 stars are members of this fine group. East of the seven sisters is the V of stars marking the face of Taurus the Bull, with bright orange Aldebaran as his eye. The V of stars is the Hyades cluster, older than the blue Pleaides, but about half their distance.

Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the NE sky until even brighter Mars rises about an hour later. It is part of the pentagon on stars making up Auriga, the Charioteer (think Ben Hur). Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor (closer to Capella, rising first about 7:30 PM as December begins) and Pollux highlight the Gemini. UWF alumni can associate the pair with Jason and the Golden Fleece legend, for they were the first two Argonauts to sign up on his crew of adventurers.

South of Gemini, Orion is the most familiar winter constellation, dominating the eastern sky by 8 PM. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. The three stars in a row that mark his belt have a Christmas association in Latin America. As "Los Tres Reyes", they stand for the three kings, bringing gifts to the Christ Child. Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery; PJC employee Jeff Ward’s shot attached shows well the tendrils of nebulosity which enchant all who observe it with large telescopes, I rank it next of Saturn as the most beautiful thing in the sky. The bright diamond of four very hot, young stars that light it up are the trapezium cluster, visible even in 60mm refractors.

For more information on the Escambia Amateur Astronomers and our local star gazes for the public, visit our website at or call our sponsor, Dr. Wayne Wooten at PJC at (850) 484-1152, or e-mail him at

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