Last modified: Thursday, December 6, 2001
Geminid meteors will highlight December
The Geminid meteor shower will peak in a dark sky on the night of Dec. 13-14, when the new moon will not obscure the bright streaks crossing the sky. If the weather is clear, conditions will be favorable for viewers.
After November's outstanding Leonid meteor shower, the Geminids will seem less of a spectacle. This year's Leonids were a special event, however, and normally the Geminid shower is the best of the year. In a clear dark sky, observers can expect to see 15-30 meteors per hour at the peak.
The meteors or "shooting stars" will seem to be coming from a point (the radiant) near the bright stars Castor and Pollux in the constellation Gemini the Twins, which gives the shower its name.
The radiant will be well above the eastern horizon a few hours after sundown and will remain high in the sky the rest of the night. Try facing southeast, though meteors will be visible in all parts of the sky.
On Dec. 14, the sun will have an annular eclipse (a ring of bright sunlight will still be visible around the moon when it is in front of the sun). This will be visible in parts of the Pacific, Costa Rica and Nicaragua. There will be a partial eclipse for most of North America, Central America, the Caribbean and northwestern South America.
An excellent source of information about all eclipses is provided by the National Aeronautics and Space Administration at http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html. It includes detailed maps and tables showing the starting and finishing times of this eclipse for many cities and the percent of the sun that will be covered in each case.
Viewing a partial eclipse can be dangerous because it's easier to gaze at the sun, since less light than usual is coming from it. But the light from the uncovered part of the sun is just as bright and intense as it is on a normal sunny day.
Ordinary sunglasses and other devices that simply reduce the amount of light coming into your eyes are no help, because they let through all of the equally dangerous infrared radiation. A safe way to view the eclipse is through a piece of No. 14 welder's glass, which can be bought for a few dollars at a welding supply store. It will block all of the sun's infrared and ultraviolet radiation and most of the visible light.
The eclipse can be viewed indirectly by poking a hole in a piece of cardboard with a slender pin and letting sunlight come through the hole onto a piece of white paper held a couple of feet away. The smaller the hole, the sharper the sun's image on the paper will be. Move the paper forward and back until the image of the sun is focused as much as possible, and you can watch the dark moon take a chunk out of the white circle of sunlight.
Brilliant yellow Saturn will be low in the eastern sky after sunset, dominating the constellation Taurus the Bull and easily outshining its brightest star, orange Aldebaran. Saturn is brighter than it has been for almost three decades, reaching opposition (opposite the sun in our sky) on the night of Dec. 2-3 and remaining about as bright for several weeks.
Even brighter Jupiter will follow Saturn, rising soon after dark at the beginning of the month in the constellation Gemini the Twins to Saturn's lower left (east). The bright stars Castor and Pollux will be on Jupiter's left (north), with Castor above Pollux. Both Jupiter and Saturn will appear earlier in the evening as the month goes by.
Mars will be the highest planet at nightfall during December, moving from the southern sky to the southwest as the evening progresses. The orange object will be faint but still easy to find this month in the dim constellation Aquarius.
Venus and Mercury will be lost in the solar glare during December. Mercury will appear in the evening sky in January.
The sun will reach its southernmost point in the sky, called the December solstice, on Dec. 21 at 2:21 p.m. EST (19:21 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.
The moon will be at third quarter on Dec. 7, new on Dec. 14, at first quarter on Dec. 22 and full on Dec. 30.