Wishing upon the Shooting Stars: The Geminid Meteor Shower

Have you been wishing for something and it hasn’t come true? Well you are in luck. The Geminid meteor shower will be giving us plenty of shooting stars (meteors) to wish upon from Dec. 4-17, and according to Ptolemy (1^st century A.D.), when there are shooting stars the gods will be looking down on us and listening to our wishes. There were will be plenty of opportunities to make wishes this week, especially during the peak viewing time on the evening of December 13 and into morning of December 14 when shooting stars will fall at a rate of 80-120 per hour! You only have a few seconds to make your wish as the meteor falls from the sky and you must say your wish out loud!

There will be a New Moon (no moon) on December 13, which is an added bonus, since no moon means less light in the night sky. Hopefully, we will have good weather too! And this annual event will be visible both in the Northern and Southern Hemispheres; however folks in the Southern Hemisphere will see the meteors at a much slower rate. Another bonus, according to NASA, is the chance to witness a new meteor shower as the Earth passes by debris of the Comet Wirtanen December 10-15. This new meteor shower is predicted to produce 10-30 meteors per hour. In case you were wondering, meteors that hit the Earth are called meteorites and, unfortunately, meteor showers do not typically produce meteorites because the particles are too small.

You don’t need to set your alarm for 2 a.m. – you can view the Geminids all evening- but after midnight will be the best show. To find them, look up to the night sky for the constellation Gemini which has two very bright stars – Castor and Pollux – also known as “The Twins.” Gemini will be above and to the left of the constellation Orion. It will be rising over the eastern horizon around sunset. Later at night you may need to gaze directly upward. If you are like me and you have a night sky ‘app’ on your mobile device, locating constellations in the sky is much easier.  If you don’t have a mobile device check out Astronomy magazine’s helpful viewing advice   or find an astronomy club near you.

Meteor showers are named after the “radiant point,” which is the area of the sky where meteors appear to shoot from.  The Geminid Meteor Shower  radiant point is the constellation Gemini. The new meteor shower will have the radiant point from the constellation Pisces. In 1833, the discovery of the Leonids phenomenon in the radiant Leo led to discovery of other meteor showers and also made meteor showers related to the study of astronomy. Up to that point meteors (small fragments of cosmic debris that burn up in the atmosphere) were thought to be a weather phenomena. This idea originated with Aristotle’s (384-322 BCE) Meteorologica, in which he proposed that meteors were a form of lightning.

In 1862, Robert Philips Greg of Manchester, England recorded 10-12 meteors “in all quarters of the sky” on Dec. 10 & 11 that had a “radiant point perfectly marked between Auriga and Gemini (Report on observations of luminous meteors, 1862-63: pg. 240-241 ).”  Professors B.V. Marsh and  Alex C. Twining of the United States also observed the Geminids that year.  These are considered to be the first ‘recognized’ observations of the Geminids, although there is evidence of earlier observations that suggest that the Geminids might have been active as early as 1833 (See W.E. Besley. The Geminid meteor shower. Observatory, v. 23, 1900: 366-370) and records from China suggest even an earlier date, that of 1533 (See Meteor showers and their parent comets by Peter Jenniskens: Historic Showers table 1, pg 609). The exact size and shape of the Geminid stream were identified in 1947 through photographic meteor studies of F.L. Whipple from the Harvard Meteor Project.

Meteor showers are associated with meteoroids (the cosmic debris or dust of a parent comet). In the case of the Geminids, the parent comet was not known until the 1980’s because there were no known comets in proximity to the Geminids orbit. On Oct. 11, 1983 Simon Green and John K. Davies noticed a rapidly moving object in the constellation Draco. The next evening Charles Kowal confirmed it to be an asteroid and designated it as 1983 TB. Then in 1984 Fred Whipple noted that the asteroid possessed a similar orbit to the Geminids. With confirmation from the scientific community the asteroid 1983 TB was given the permanent designation of 3200 Phaethon. This was the first time an asteroid was linked to a meteor shower. However, NASA scientist Bill Cooke from the Meteoroid Environment Office believes 3200 Phaethon might be an extinct comet (a comet that has lost its ice) or a rock comet (an asteroid that has gotten too close to the sun.)

As the Earth crosses a comet’s orbit the meteoroids clustering along the comets orbit can produce meteor showers. The Geminids may decrease as 3200 Phaethon gets pulled away from Earth’s orbit by Jupiter’s gravity. By the end of this century the citizens of earth may not be able to witness the Geminids and for our descendents,  about 250 years from now, 3200 Phaethon will come close enough to Earth’s orbit to be visible to the naked eye.

For a more in-depth discussion see Geminids in Meteor Showers and their Parent Comets by Peter Jenniskens (Cambridge, Cambridge University Press, 2006): 397-422. Also, the Library of Congress has a wealth of material (old and new) related to meteors, such as catalogs of observations during the 18^th and 19^th centuries. For online information about meteor showers you might want to check the Science Reference Section’s Internet Resources to Meteor Showers

So get outside, find a shooting star, and make a wish or two!