The Night Sky for December 2007
A Starwatching Guide to Planets, Meteor Showers and More
Comet Holmes is slowly fading as an observing target, now rapidly dimming after its original outburst. Comet Holmes remains in the constellation Perseus. You can find the constellation in between the W-shape of Cassiopeia and Taurus and the Pleiades cluster, which are in the northeast. Use binoculars to spot the comet. It will be the large, fuzzy, and diffuse object among the surrounding stars. At this point you may only notice a slightly lighter color in the background sky that marks the comet's presence. Comet Holmes first started spewing out excess gas and dust at the end of October and since then it has ejected such a large bubble around it that it is now the largest object in the solar system, surpassing even the sun. Read more about Comet Holmes and how to find it.
December Meteor Showers
Two meteor showers highlight the month of December. The first is the Geminid meteor shower, which peaks on December 13 and 14. The Geminid meteors are one of the best showers of the year. With a ZHR (zenithal hourly rate) of up to 80 meteors an hour, its worth bundling up to go out and take a look. The meteors should appear to come from the constellation Gemini, which will be rising in the east-northeast in the early evening. Instead of a comet, the debris that causes the Geminid meteor shower comes from an asteroid named Phaethon.
The second meteor shower peaks on Christmas Eve, December 24. This quieter meteor shower only produces about 9 meteors an hour. Called the Ursids, the meteors appear to come from the constellation Ursa Minor, or the Little Dipper. The Ursid meteors are the result of debris from Comet Tuttle.
The December Solstice
In the Northern Hemisphere, winter begins at 1:08 am EST on December 22. Earth's Northern Hemisphere is now titled farther away from the sun, bringing less sunshine and warmth, while the Southern Hemisphere is tipped toward the sun, bringing them summer. So while people in the Northern Hemisphere call this solstice the winter solstice, in the Southern Hemisphere its the summer solstice.
If you are watching the sun during sunrise or sunset, you'll have noticed that the sun moves farther toward the horizon each day. On the solstice the sun appears to halt this movement and stand still. It will slowly begin to creep back toward the north over the next few months.
Planets for December 2007
Mars is at its best for the year in December. The Red Planet shines brilliantly in the northeast after sunset. Mars reaches its peak of brightness between December 18 and December 24 at magnitude -1.6, brighter than Sirius! Mars gets closest to Earth on December 18, a mere 54.8 million miles away. December 24 is the date of opposition, when Mars is opposite the sun in our sky. Opposition is a great time to view any planet, because it is up all night long.
On December 23 the moon appears just below Mars. The moon is also full on this date at 8:16 pm EST. New Moon occurs on 12:40 pm EST December 9. Look for a young crescent moon on December 11 just after the sun sets.
Jupiter remains low in the southwest in the early evening. It shines at magnitude -1.8. Venus continues to play the part of morning star in the southeast. It's stunning magnitude -4 reigns in the morning hours until the sun rises. Saturn rises in the late evening at the beginning of the month but a little earlier each night. Saturn lies in the constellation Leo very near the star Regulus.
The Star of Bethlehem
The Star of Bethlehem is an important part of the story of Christmas. What was this mysterious star that led the wisemen and can it be explained through astronomy? Read more about this wondrous sight.
