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Posted at 09:36 AM ET, 12/13/2012

Geminid meteor shower reigns tonight, thanks to a cosmic rocky road

In many ways, Thursday night’s peak of the Geminid meteor shower will rock.

While the Perseid meteors in August snare more media attention, Thursday’s Geminid meteors almost always outperform them, says Geoff Chester, of the U.S. Naval Observatory. Unlike other meteor showers, where the parent is a frozen comet, this one traces lineage to a cosmic rock.

With hope of clear skies and no contentious moon Thursday night, go outside and look up. That’s all. No telescopes, no binoculars, it’s just your eyes. Stay away from front porch lights, backyard beams and street lamps. Find a hot beverage to sip, get your eyes acclimated to the dark and then gaze. The best time will be between 10 p.m. and 2 a.m., says Chester.


A Geminid meteor streaks between peaks of the Seven Sisters rock formation in the Valley of Fire State Park in Nevada in 2010. The shower is visible every December. (Ethan Miller - Getty Images)

The Geminids get their names since they appear to emanate from the constellation Gemini. The International Meteor Organization (IMO.net) predicts the zenithal hourly rate might be 120 meteors an hour, at peak. Persistent sky gazers may spot dozens in a dark location. Generally, though, you may be able to spy around 20.

Meteor mania: Alan MacRoberts, senior editor at Sky & Telescope magazine, explains that Geminid particles travel at 22 miles per second in the upper reaches of the atmosphere. The Naval Observatory’s Chester says the Geminids — when compared to Perseids — are relative slowpokes. You’ll see them streak through large regions of the night sky — sometimes leaving a faint smoke train from their passage, he says.

Science@NASA has produced a video, called “Rock Comet Meteor Shower,” that provides a visual explanation of Thursday’s Geminid meteor shower.

Periodically throughout each year, the Earth runs into streams of dust left behind by icy comets. When the Earth runs through these dirty trails, specks of dirt strike our atmosphere and burn up — giving us wonderful meteors. But, the Geminids’ dusty trail was not left by a traditional icy comet. Instead, these meteors came from an asteroid called 3200 Phaethon (pronounced fay-a-thon) — which was discovered in 1983 via the Infrared Astronomical Satellite, or IRAS.

A quarter-century later, UCLA astronomers David Jewitt and Jing Li, used NASA’s STEREO-A spacecraft to watch Phaethon as it toured near the sun in mid-June 2009. They observed Phaethon approaching the sun, and saw that the solar heat caused the object to brighten — and the rock was emitting particles. After their observations, Jewitt and Li now suggest “that Phaethon is essentially a rock comet.”

In other words, instead of dirty ice falling off a snowball-like comet, Phaethon throws off little specks of rock and this ejecta (through heat fracturing) leaves a trail in interplanetary space. (Source: “Activity in Geminid Parent (3200) Phaethon,” in the Astronomical Journal, Nov. 2010)

After Thursday’s major gift from the heavens, don’t fret. December has a stocking stuffer left. While small, the Ursid meteors peak during the morning of Dec. 22. It’s a tiny shower, where the zenithal hourly rate is predicted at 10 meteors, says the IMO. However, this shower has been known to surprise astronomers in recent years with dozens of meteors at peak.

By Blaine Friedlander  |  09:36 AM ET, 12/13/2012

Categories:  Latest, Astronomy

 
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