Asteroid Debris and the Giminid Meteor Shower
The Geminid meteor shower is active every year from December 7 until December 17, but the pre-dawn hours of December 13 and 14 should be the best time to watch. Although Geminid meteors usually shoot from a radiant point in the constellation Gemini, just keep scanning the skies to catch a glimpse from a trail of streaking light.
Most meteor showers happen when Earth passes through the debris trail of a comet. The Geminids are different and somewhat of a mystery. These meteoroids appear to come from 3200 Phaethon, an asteroid. Asteroids are large pieces of either rock or rock and metal. They are fragments of small planets that were shattered in collisions with each other early in the history of the solar system. Comets, on the other hand, are chunks of ice and dust that evaporate when they approach the sun.
Giminids look like most meteors in that they tend to be fast moving and yellow in color. Stargazers first noticed the Geminids in the mid -1800's. Then, in 1983, NASA's Infrared Astronomy Satellite spotted a new asteroid: 3200 Phaethon. Astronomer Fred Whipple realized that Phaethon and the Geminid meteoroid stream followed nearly identical orbits. It seemed that the asteroid Phaethon moved around the sun in a one and a half-year elliptical path that stretched from inside the orbit of Mercury outward toward the asteroid belt that is located between the planets of Mars and Jupiter.
Phaethon's sun grazing orbit might be responsible, in part, for the Giminids. It could be that a lump of dusty ice on the surface of Phaethon was uncovered at some point and then vaporized by solar heating. Such an event might produce meteoroids in the style of a comet.
Every year in mid-December when the Geminid meteor shower is active, Earth is barely eight lunar distances from Phaethon's orbit. That makes Phaethon a very near- Earth asteroid and gives stargazers here in the Waynedale area an opportunity to see some of its ancient debris as it streaks across the sky as meteors.
The Giminid meteors should shower at rates of up to one a minute (if you are in a very dark, rural sky) from about 10p.m. to dawn on the nights of December 12th and 13th and again on December 13th and 14th. Simply scan the skies back and forth. The absence of moonlight makes this year's Giminids definitely worth a look. Hopefully we won't be socked in with fog as we were for the Leonids in November.
I wish you all a very Merry Christmas. May you be renewed with the hope once announced to this planet so long ago by the bright Star of Bethlehem. May that Light radiate from our hearts so that this fragile Earth might be a more peaceful place for all creation.