Check out the spectacular show of Geminid meteor showers this week.
From Denny: You know you are smitten with astronomy when you are willing to brave the December night cold just to look up and view the sky. Well, tonight and tomorrow night you will not be disappointed for all your inconvenience. The Geminids are considered the best view of all the annual meteor showers to see.
November had the Leonid meteor shower and where I live it was cloudy and a washout. Bummer. But tonight is clear and oh, so very cold thanks to "the lake effect" weather coming down in an Arctic blast from the Great Lakes region. Why is it the best sky viewing is always when it's stone cold? :) The Geminid meteor shower reaches its peak show-off performance tonight and tomorrow so make sure to get out there to take a look.
As you guessed the Geminids are named for the constellation of good ol' Gemini, also known as the Twins to astrologers. To those of us gazing up at the night sky from Earth it will appear the shooting stars originate from this constellation. The shooting stars will appear to emanate from an area nearest the bright star of the Gemini constellation called Castor.
Check out this sky map for best viewing about 1 AM EST on 14 Dec 2010 when the shower peaks.
What causes a meteor shower?
The vast majority of meteor showers tend to be caused by the fragments of old comets that get scattered along the comet's orbit. As our Earth passes through a comet's orbit, it gathers up those fragments. The fragments get heated up by friction with our planet's atmosphere to incandescence, now becoming visible as very bright streaks of light.
Of course, just like the personality for which they are named, the Geminids like to be different. They do not originate from a comet but from an asteroid called 3200 Phaethon. This asteroid is one odd duck too. It likes to take chances, like orbiting closer to the sun than any other known asteroid, even to the point of getting inside the orbit of planet Mercury. It dances in its orbit like a comet instead of like an asteroid. Yet Phaethon cannot be called a comet. A comet is defined with features like a dust tail, a gas jet and a coma. Phaethon exhibits none of these features. Some astronomers believe Phaeton may be the dead nucleus of a burned-out comet that somehow got trapped into an unusually tight orbit.
You will be able to see the meteor showers all night long in various places in the night sky. The showers will be faster and brighter after midnight. The moon will set very close to midnight which will allow the fainter meteors to be better viewed.
Facts about the Geminids
Here's are a couple of curious facts about the Geminids. They move slower than their summer cousins, the Perseids. An amusing fact is that the Geminids often end their streak across the sky with a tiny explosion so you actually may hear a distinct popping sound.
Geminids of the past have often displayed as slow, bright and graceful meteors, even fireballs. Many have appeared as yellowish in color. Some form jagged or divided paths. Geminids are also far denser than the typical comet dust flakes from the usual commonplace meteor showers, weighing in at about .07 pounds per cubic inch or 2 grams per cubic centimeter. Gemini is well named for it likes to impress. Their speed in slower than the Leonid showers, clocked at about 22 miles per second or 35 km. This slower speed makes it possible for them to linger in the sky a bit longer for enjoyable viewing.
Usually, our planet moves quickly through a meteor stream. The general rule is that the rate of meteors increases steadily for about two to three days before hitting its height. Then it will drop off sharply, lasting for about a day or so after the peak.
Geminids and best viewing
The fun about these December Geminids is not only are they especially bright for easy viewing, there will be a few renegade forerunners and late stragglers for a good week or more both before and after the peak time. Astronomers have just recently discovered that the Geminids are appearing as early as November 30, something unexpected.
The peak time will be closer to sunrise on 14 December 2010 at about 6 AM EST. You can expect to see any where from about 60 to 120 Geminid meteors about every hour. Here in North America - it was about time - we get to be the ones best situated to view this wonderful sky event at the crest of the shower. Even though the moon will still interfere with its light, you will be able to view some meteors as early as 10 PM. This meteor shower stream is considered to be "young" - only a few thousand years old. I guess the Geminids have had plenty of time to perfect their showing off. Check out the sky gems!
*** Photo by Wally Pacholka of AstroPics.com, a Geminid fireball explodes over the Mojave Desert on Dec. 13, 2009