Credit: Wally Pacholka TWAN

WHAT: Geminid Meteor Shower

WHEN: December 13 / 14

WHERE: The Night Sky!

While Gemini currently rises from the east horizon around 9pm, tonight’s first-quarter moon sets around 1am local time, when Gemini is higher overhead, so best observations will likely be in the hours between 2am and dawn, local time.

Don’t overlook tonight’s first-quarter Moon with Jupiter, earlier in the evening, and all those celestial goodies surrounding Gemini, throughout the night!

If your skies are too cloudy to see the Geminids, you can listen to their radar echoes on Spaceweather Radio!

NASA is hosting an all-night Geminids webchat, from 11pm – 5am EST, where you can have your questions answered by  NASA astronomer Bill Cooke!

Twitter-users are including the #Geminid hashtag to share their observations from around the world.

Photograph tonight’s meteor shower with helpful hints from this article, by Dennis Bodzash.

Collect tonight’s meteor shower with this micrometeorites how-to from Brian Carusella.

Contribute to meteor science with the International Meteor Organization’s electronic visual report form, here, and the American Meteor Society’s fireball reporting form, here.

FUN FACTS:

Meteor showers occur when our planet encounters the debris fields of passing comets.  Much of the debris is dust-sized particles, but some streams can contain larger objects ranging from gravel to small rocks.  Individually, these particles are known as meteoroids.

Most debris fields are ancient, having been left tens and hundreds of years ago, by comets as they near the Sun.  As the material leaves a comet, it falls into orbit as a collective stream or elongated patch.  Some streams can extend for millions of miles.

As Earth moves through a comet’s debris field, those particles (meteoroids) passing through our atmosphere are vaporized, resulting in the bright streaks that we call meteors.

Meteoroids that survive their encounter with our atmosphere, and actually impact the Earth’s surface as a small rock, are known as meteorites.

Meteor showers are named for the constellation from which the meteors appear to emanate, rather than for their physical origins.  That apparent, or visual, origin point is known as the “radiant.”

Observed nearly every December since the late 1800s, the Geminids are named for the constellation Gemini, with their radiant appearing to be just north of Gemini’s two brightest stars, Castor and Pollux.

Although Geminid meteors are slower and exhibit less trails than most other meteors, Geminids put on a fantastic display as one of the more prolific and consistent meteor showers of the year.

Geminids activity has steadily increased through the decades, with plateau peak rates reaching as high as +/-120 in more recent years.  A 2005 analysis of sixty years of observation data suggests the Geminid stream to be about 6,000 years old.

A meteor shower’s physical origin is known as the “parent body” or “progenitor.”  Geminid meteors originate in Earth’s encounter with the debris field of the near-Earth-object, 3200 Phaethon.

The Geminids’ progenitor, 3200 Phaethon, became the first asteroid discovered by a spacecraft, when scientists spotted it in images from the multi-national Infrared Astronomical Satellite (IRAS.)  Those scientists were Simon F Green and John K Davies, and the year was 1983.

3200 Phaethon is categorized as an Apollo class near-Earth-object, as well as a potentially hazardous asteroid (PHA,) with its closest pass missing Earth’s orbit by a mere 2-million miles.

Although most meteor showers do originate from comets, 3200 Phaethon is not a typical comet, nor does it appear to be a usual asteroid.  While some scientists originally thought that Phaethon may be a “dormant” comet, a more recent study proposes an entirely new kind of object – a “rock comet” possibly even born of an impact event with the large main belt asteroid, Pallas.

A better understanding of Phaethon’s peculiar comet/asteroid characteristics and possible Pallas relationship might also help scientists make more learned determinations about other similar peculiar events, such as the recent comet-like coma detected around the asteroid (596) Sheila.