Skywatchers, grab your blankets. December's night skyspectacular will feature the best meteor shower of 2010 as well as the only totallunar eclipse of the year ? sights that should outshine any New Year's Eve fireworksdisplay in terms of sheer wonder.
The massive Geminidmeteor shower returns every year, so you'll have more chances if the coldproves too daunting on the night of Dec. 13. But anyone in North America who skipsthe total lunar eclipse on the night of Dec. 20 will be missing what promisesto be the best lunar eclipse show until April 2014.
This year's Geminid meteor shower is expected to be the bestdisplay of so-called "shootingstars" of the year and will peak during the overnight hours of Dec. 13and Dec. 14.
Dazzling Geminid meteor shower
Like most meteor showers, the Geminids will be at their bestafter midnight (early on the morning of Dec. 14), when the Earth is headingdirectly into the meteoroid stream. But some will be visible earlier in thenight, on the evening of Dec. 13, because the meteors' radiant ?(where theyappear to originate) is nearly circumpolar, so they will stay in view above thehorizon all night.
Thissky map shows where to look to see the Geminid meteor shower in thedirection of the constellation Gemini. Clear dark skies, of course, promise thebest viewing conditions.
Anyone venturing outside should dress much more warmly thannormal to prepare for a long night vigil while sitting still.
Don't forget to get comfortable: A lawn chair with areclining back and a blanket or sleeping bag should keep skywatchers snug ? nobinoculars or telescope are necessary.
Most meteor showers are caused by fragments of old cometsscattered along a comet's orbit. When the Earth passes through a comet's orbit,it sweeps up the fragments, which become visible as bright streaks of light inthe atmosphere.
The Geminid shower is unique in being associated not with acomet, but with an asteroid called 3200 Phaethon.
The Geminids' radiant is, as the name implies, in thedirection of the constellation Gemini, just north of the northernmost ofGemini's two brightest stars, Castor and Pollux. In the early evening of Dec.13, the radiant is low in the northeast. By 1 a.m. EST, after the date haschanged to Dec. 14, the radiant is almost directly overhead. By 6.a.m. EST,when the shower is at its peak in the Eastern Time Zone, the radiant is low inthe west.
Moon's holiday treat
The December holiday sky show doesn't end with the Geminidmeteor shower. On the nights of Dec. 20 and Dec. 21, parts of four continentswill be treated to a total eclipse of the moon ? the only one to occur in 2010.
This NASAlunar eclipse chart shows the visibility of the eclipse from differentregions around the world.
The last total lunar eclipse occurred on Feb. 20, 2008. Whilethere are two total lunar eclipses in 2011, North American skywatchers willhave to wait until April 2014 for one as potentially spectacular as the eclipseoccurring this month. [AmazingTotal Lunar Eclipse Photos]
Lunar eclipses occur when the moon passes through a point inits orbit in which the Earth is directly between it and the sun. When the moonenters the shadow of Earth, it creates a lunar eclipse. Unlike a solar eclipse,no precautions to protect the eyes are needed.
A totallunar eclipse is when the entire moon is completely inside the Earth'sshadow. Since the sun's rays are bent by Earth's atmosphere so that some stillreach the moon, the moon is still visible in an eclipse.
Lunar eclipse skywatching tips
For the Western Hemisphere, the eclipse will"officially" begin on Dec. 21 at 12:29 a.m. EST (9:29 p.m. PST onDec. 20) as the moon begins to enter Earth's outer, or penumbral, shadow.
As for the Geminid meteor shower, don't forget to dresswarm. But you won't be outside all night moongazing. This total lunar eclipse lastsonly 72 minutes from start to finish.
But even in clear weather, skywatchers will not notice anychanges in the moon's appearance until about 45 minutes into the event, when aslight "smudge," or shading, begins to become evident on the upperleft portion of the moon's disk.
The entire total lunar eclipse will be visible from all ofNorth and South America, the northern and western parts of Europe, and a smallpart of northeast Asia, including Korea and much of Japan.
Totality will also be visible in its entirety from the NorthIsland of New Zealand and Hawaii. In all, an estimated 1.5 billion peoplewill have an opportunity to enjoy the best part of this lunar show.
In other parts of the world, only the partial stages of theeclipse will be visible or the eclipse will occur when it's daytime and themoon is not above their local horizon.
Portions of western Africa and central Europe can catch theopening stages of the eclipse before the moon sets below the horizon during themorning hours of Dec. 21, while the eastern third of Asia and central andeastern Australia can catch the closing stages just after moonrise on theevening of Dec. 21.
December's total lunar eclipse and Geminid meteor showerpromise to ring the year 2010 out with a dazzling show, weather permitting,this holiday season. But bundle up and stay warm!
- Gallery: Photos of the Feb. 2008 Total Lunar Eclipse
- Top 10 Lunar Eclipse Facts
- Best Meteor Shower of 2010 Arrives in December
SPACE.com Skywatching columnist Joe Rao and Starry NightSoftware's Geoff Gaherty contributed to this December skywatchingtips report.
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