Purple RainThe best meteor shower of 2007 — the Geminid Meteor Shower — is upon us. The Geminids are active from approximately December 6th through 19th. For the next few days their average rate is pretty low, but will slowly increase until the evening of December 13th, when the rate will significantly multiply. During the shower’s peak, which runs from about midnight through dawn the next morning (14th), you may see 60-75 meteors per hour, if you are observing from a cloud-free dark location, away from city lights. Light interference from the moon will not be an issue, as the moon is only a four-day-old crescent.
Meteor showers are named for the constellation from which they seem to radiate — in this case Gemini, the Twins. First recorded in 1862, the Geminids are relatively new as meteor showers go. The first estimate of their strength, in 1877, revealed an average of 14 meteors per hour. Since then, the rate has steadily increased, with estimates of 23 in 1896, 40-70 in the 1930s, 60 in the 1950s and 65 in the 1960s.
On any given night, you may see random meteors when celestial debris sporadically enters Earth’s atmosphere. Meteor showers are more predictable and include many meteors rather than an occasional few. They typically occur when comet debris crosses Earth’s orbit. In fact, many meteor showers are linked to specific comets. For example, both the Orionid and Eta Aquarid Meteor Showers derive from remnants of Halley’s Comet.
The Geminids, however, appear to be an exception to the link with comets. In 1983, astronomers discovered a celestial object now known as 3200 Phaeton. Its orbit matched that of the Geminids, thus giving reason to believe that this object is the source of the Geminid Meteor Shower. However, 3200 Phaeton may not even be a comet. It has a rocky surface, and the meteors it appears to produce are much denser than those typically created by a comet. Some scientists have suggested this body may be an asteroid. Since asteroids are rocky, though, they do not have tails as comets do, and thus do not produce meteor showers. Perhaps 3200 Phaeton got a tail by bumping into another asteroid, creating a debris cloud? Another possibility is that 3200 Phaeton is actually a dead comet. Perhaps all its ice vaporized by repeated close approaches to the Sun, resulting in the rocky core and remnants of a tail?
Whatever the nature of 3200 Phaeton, the meteors produced by its debris are fun to learn about and see. At 7:00 p.m. on Wednesday, December 12, Lowell Observatory will offer a special indoor presentation about the Geminids, including how, when and where to best see them. If the weather permits, telescopes will also be set up to view other celestial objects (it is difficult to view meteors through telescopes.)
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