Feature Article December 4, 2003
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Five Bright Planets and A Christmas Day Conjunction
In the month of December, in this part of the world, the times of sunset vary by only about 10 minutes over the whole month. At the first of the month, the sun sets at 4:25 p.m., and the years earliest sunset is at 4:24 p.m. on December 10. Thereafter it is only seconds later each evening until the end of the month, when it is at 4:33 p.m. Many people find it interesting to learn that the earliest sunset is not on December 21 or 22, which is the date of the Solstice, which means the sun standing still. Of course, Solstice is the time when one can notice the southward movement of the sun stopping and its northward movement starting, an observation that is best made by carefully watching over several days, from exactly the same place, the exact place on the horizon where the morning sun rises or the evening sun sets. Sunrises this month are a little later each morning, from 7:25 a.m. on Dec. 1, to 7:47 a.m. on Dec. 31, and the latest sunrise of the year, in this part of the world, is not until January 3.
Just as the sun appears weaker and farther south in December, so also the Full Moon nearest the December Solstice, always being in the opposite part of the sky, appears highest and furthest north of any Full Moon in the whole year. Watch the Full Moon of December 8 - 9 to see it rising, not in the east, but in the northeast, and appearing almost straight overhead at midnight, rather than down in the southern sky, and finally setting in the northwest, rather than in the west, as morning approaches.
It is also the month to enjoy the brilliant star patterns in the late evenings southern sky. Foremost among them are Orion, the Great Hunter, marching across the heavens, followed by his friendly dogs, Canis Major, whose eye-star Sirius is the brightest star in the sky, and Canis Minor, whose eye-star Procyon is the sixth-brightest star. The brilliant stars marking Orions shoulders, knees, and belt have been known and named by our ancestors for thousands of years. Above Orions shoulder and the stars marking his outstretched arm and shield, it is easy to recognize the large cluster called the Hyades, which marks the head of Taurus the Bull. On the bulls back ride the Pleiades, the beautiful cluster that is also known as The Seven Sisters. Compare the Hyades and Pleiades clusters, noting how much looser the former is and how much more compact the latter is. Many people have noted for centuries that Cygnus the Swan, which flew overhead in the summer and early autumn sky, is now a Cross standing above the northwestern sky; the constellation is called The Northern Cross, as well as The Swan, and some have seen it as a Christian symbol appropriate for the Christmas season.
Among the bright planets, Mars may be the first one noticed in the southern evening sky. Its reddish gleam still dominates that part of the sky, but it is definitely not as bright as it was in the late summer and it will fade more in the coming months. However, if one has a good view toward the southwestern horizon, the first object seen will likely be brilliant Venus, which will pop into view shortly after sunset and may be seen for about two hours before it sets. For the first half of the month the planet Mercury may be seen slightly down and to the right from Venus. Try to make a real effort to see Mercury this month, because this planet, which is seldom seen by many people, will be quite easy to find, being so close to Venus. However, Mercury will not be visible in the last week of the month. A short while later in the evening, the planet Saturn may be seen rising in the east in the constellation Gemini and a bit to the right of the very bright stars Castor and Pollux. The fifth of the bright planets to appear, Jupiter, which is actually the largest of all the planet and the one that appears second in brightness after Venus, will come up in the east at about midnight in the first part of the month and at about 10:30 p.m. in the latter part of the month. Jupiter appears in the constellation Leo the Lion and dominates the eastern sky from midnight until dawn.Be sure to watch the moon near Saturn on the nights of Dec. 10 and 11; in fact, on Dec. 11 it is also quite near the star Pollux. On Dec. 15 try not to miss its appearance very close to the planet Jupiter. On Dec. 24, Christmas Eve, challenge yourself to spot the very slim crescent moon just above the southwestern horizon about an hour after sunset; it will be below Venus and slightly to the right. Less of a challenge will be the VERY beautiful sight on Christmas Day one hour after sunset, when the crescent moon appears just to the left of Venus above the southwestern horizon. As you finish your Christmas dinner, remind yourself to observe this close conjunction of the night skys two brightest objects. On Dec. 29 the First Quarter Moon appears below Mars, another sight that is well worth viewing.
Even though moonlight may interfere somewhat, be sure to watch for the peak of the Geminid Meteor Shower on the nights of Dec. 13 and 14, especially after midnight and especially in the southeastern sky. You may see dozens of bright shooting stars, if you observe for an hour or more.
More detailed information about observing the winter constellations and other objects of the night sky is found in the book The Beginners Observing Guide, available at Sharbot Lake Pharmacy. It is for young and old, and could be a good Christmas gift suggestion. I wish all readers clear, unpolluted, dark skies, and a very safe and merry Christmas holiday.
