Wednesday, December 13, 2006

Meteor Showers -

The 2006 Geminid Meteor Shower
The best meteor shower of the year peaks this week. Start watching on Wednesday evening, Dec. 13th. The display will start small but grow in intensity as the night wears on. By Thursday morning, Dec. 14th, people in dark, rural areas could see one or two meteors every minute.

The source of the Geminids is a mysterious object named 3200 Phaethon.

The mystery, properly told, begins in the 19th century: Before the mid-1800s there were no Geminids, or at least not enough to attract attention. The first Geminids appeared suddenly in 1862, surprising onlookers who saw dozens of meteors shoot out of the constellation Gemini. (That's how the shower gets its name, the Geminids.)

Astronomers immediately began looking for a comet. Meteor showers result from debris that boils off a comet when it passes close to the Sun. When Earth passes through the debris, we see a meteor shower.

For more than a hundred years astronomers searched in vain for the parent comet. Finally, in 1983, NASA's Infra-Red Astronomy Satellite (IRAS) spotted something. It was several kilometers wide and moved in about the same orbit as the Geminid meteoroids. Scientists named it 3200 Phaethon.

Just one problem: Meteor showers are supposed to come from comets, but 3200 Phaethon seems to be an asteroid. It is rocky (not icy, like a comet) and has no obvious tail. Officially, 3200 Phaethon is catalogued as a "PHA"-a potentially hazardous asteroid whose path misses Earth's orbit by only 2 million miles.

If 3200 Phaethon is truly an asteroid, with no tail, how did it produce the Geminids? "Maybe it bumped up against another asteroid," offers Cooke. "A collision could have created a cloud of dust and rock that follows Phaethon around in its orbit."

So, are the Geminids an "asteroid shower"?
The object's orbit carries it even closer to the Sun than Mercury. Extreme solar heat could've boiled away all of Phaethon's ice long ago, leaving behind this rocky skeleton "that merely looks like an asteroid." - In short, no one knows. It's a mystery to gaze upon, under the stars.

Some scientists have said that the impact of a large meteorite in the Yucatan Peninsula, in what is today Mexico, caused the mass extinction of the dinosaurs, along with the majority of all other animal species on Earth, approximately 65 million years ago. Others argue that there must have been additional meteorite impacts or other stresses around the same time.

A new study provides compelling evidence that "one and only one impact" caused the mass extinction.

Read more A Single Meteor Impact Killed The Dinosaurs
Gemini is one of the constellations of the zodiac. It is part of the winter sky, lying between Taurus to the west and Cancer to the east.

A myth of these twins concerns cattle theft, and may be connected to early views of the Milky Way, as a herd of dairy cows -
The orientation of the constellation can vary (they readily form stick figures whether leaning right or left), though the twins are usually viewed as left leaning. However, when right leaning, one of the twins resides in the Milky Way, and the other outside it, a situation making it appear that one of the twins is stealing the cattle, and the other is observing.
We were all made of supernovae Podcast @ Universe Today
Heavy stars embedded in NGC 6357 read more @ Universe Today
What makes the biggest impact on galactic evolution @ Universe Today

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