Path of the Earth through the Giacobinid streams. (Graphic by Author).
A total wild car meteor shower may be just around the bend. The Draconid meteor shower is usually obscure even on a good year, with rates in the 5-10 per hour doldrums. This peak usually occurs on or around October 8th, and passes with nary a notice. This shower has, however, been prone to sporadic outbursts of storm level intensity. 2011 might just be one of those years. On the night of October 8th-9th, our orbit will transect two meteor debris paths of comet Giacobini-Ziner, namely a 1900 stream and a 1873-94 stream. Historically, the Draconids (sometimes also referred to as the Giacobinids) reach storm intensity, with peaks in access of 10,000 per hour observed in 1933 and 1946. Even in 1998, observers caught a respectable 600+ per hour, and more recently in 2005 an enhanced rate triple the usual average was seen… could 2011 be a storm year? Expert predictions run the gamut for multiple peaks from 17:09UT to 20:36UT on the 8th with 500 to in access of 1,000+ meteors per hour. This would place the best chances of observing as northern Europe eastward, but anywhere worldwide should be vigilant. The good news for northern hemisphere observers is that the Draconids have a very high radiant of declination +54° degrees north in the head of Draco, and thus are one of the few showers that may get into high gear before local midnite. The bad news is that the Moon will reach Full only a few days after the shower peaks on October 11th, and thus will cut down actual observed rates significantly. Several observation campaigns are planned, and engineers at NASA are also accessing the possible concerns that the 2011 Draconids may pose for spacecraft and the International Space Station.
This astronomy term for this week is Meteor Shower. This is simply an event where meteors seem to emanate from one point in the sky known as a radiant. This motion, of course, is largely due to the path of the Earth sweeping up meteors in its orbit. The very term meteor shower shows that the ancient idea that meteors are exclusively atmospheric phenomena like lightning or tornadoes is still largely with us. Most known showers are related to dust left from the passage of comets, and range in intensity from 5 per hour to great swarms in access of 10,000 per hour. Some of the most dependable annual meteor showers are the Perseids and the Geminids, while some of the great outbursts in history have come from the Leonids and the Draconids.