Last modified: Wednesday, December 1, 2004
Year's best meteor shower and occultation of Jupiter
BLOOMINGTON, Ind. -- The Geminid meteor shower is reliably the best of the year, but you have to brave the cold of a December night to see it. So it is less well known than the Perseid shower of August, when the hazard is mosquitoes instead of frostbite.
The Geminid shower will peak on the night of Dec. 13-14, just two days after the moon is new. The moon will cooperate even more by setting as the peak begins, so moonlight won't interfere at all. If clouds don't get in the way, skywatchers can expect to see 60-70 meteors per hour at the peak and perhaps more, with a number of bright ones in addition to the fainter streaks that are obscured by bright moonlight or city lights. Start watching at midnight local time to see the most activity, though some meteors will appear as soon as the sky is completely dark.
The meteors or "shooting stars" will seem to be coming from a point called the radiant near the bright stars Castor and Pollux in the constellation Gemini the Twins, which gives the shower its name. Also nearby will be the bright yellow planet Saturn, which will outshine the neighboring stars. The radiant will be well above the eastern horizon a few hours after sundown and will remain high in the sky for the rest of the night. The higher the radiant is above the horizon, the more meteors there will be. Try facing southeast if you have a clear view in that direction, though meteors will be visible in all parts of the sky. For details about the Geminid shower, see http://comets.amsmeteors.org/meteors/showers/geminids.html.
To stay comfortable in the frigid night, wear several layers of your warmest clothing and keep a thermos of hot coffee, tea or chocolate handy. If necessary, go indoors from time to time to warm up. No special equipment is needed to watch a meteor shower. Just relax and enjoy the spectacle as the bright objects flash across the sky.
More information about meteor showers is available at http://comets.amsmeteors.org/, a site sponsored by the American Meteor Society.
On Dec. 7 before dawn, the crescent moon will pass in front of the brilliant white planet Jupiter low in the eastern sky, an event called an occultation. The moon frequently occults stars as it crosses the sky each night, but occultations of bright planets are quite rare.
This one will be visible in most of eastern and central North America, but sunrise will overpower it before viewers farther west have a chance to see it. Parts of southern Africa will also be able to witness the occultation as Jupiter slowly approaches the bright edge of the moon, disappears for about an hour, and then comes back into view from behind the moon's opposite dark edge.
Details of the event are available at http://www.lunar-occultations.com/iota/1207jupiter.htm, including a map showing where the occultation will be visible and its exact time for various cities. For those watching in Indianapolis, for example, Jupiter will disappear behind the moon's edge at 4:54 a.m. EST.
Bright yellow Saturn will appear low in the eastern sky soon after sunset, dominating the constellation Gemini the Twins. The familiar constellation Orion the Hunter will be on Saturn's right (south) at this time. Those with telescopes can view the planet's famous rings, which are tilted toward Earth. Saturn will be visible almost all night, but the best views will be when it is high in the southern sky around midnight.
A small telescope should also show Saturn's biggest moon, Titan, which is larger than the planets Mercury and Pluto. On Dec. 24, the Cassini spacecraft that is orbiting Saturn will release the European Space Agency's Huygens probe. Huygens (pronounced HOY-genz) will descend to the surface of Titan on Jan. 14, providing a good view of the giant moon's surface for the first time in history.
Even brighter Jupiter will rise in the east around 3 a.m. local time at the beginning of the month. Jupiter will be in the constellation Virgo the Maiden, easily outshining its brightest star, Spica.
Venus and Mars will clear the east-southeastern horizon close together about two hours before sunrise at the beginning of the month. They will be closest on Dec. 5, though Venus will be several hundred times brighter than small, pale orange Mars. The two planets will separate as the month advances, with Venus drifting lower as Mars climbs upward.
After passing between Earth and the sun on Dec. 10, Mercury will rapidly climb out of the solar glare into the morning sky during the last three weeks of the month, appearing to the lower left (east) of Venus. The two planets will approach each other until Dec. 27, when they will have a close encounter very low in the southeast an hour before sunrise. Nearby on their right (south) will be the bright orange star Antares in the constellation Scorpius.
The sun will reach its southernmost point in the sky, called the December solstice, on Dec. 21 at 7:42 a.m. EST (12:42 Universal Time). This will mark the start of winter in the Northern Hemisphere and summer in the Southern Hemisphere. For the next six months, the days will be getting longer in the Northern Hemisphere. Information about the solstice, including the fascinating human history associated with it, is available at http://www.candlegrove.com/solstice.html.
The moon will be at third quarter on Dec. 5, new on Dec. 12, at first quarter on Dec. 18 and full on Dec. 26.