The Earth travels through several major predictable dust belts each year. The dust produces tiny burning streaks as it passes into the Earth's atmosphere, burning up with the heat of entry and appearing as "shooting stars," as shown in the lower color insert on page C-1. These dust belts are left by passing comets in their orbits. Both the Eta Aquarid and the Oronid meteor showers are thought to be created from dust left by Halley's comet, the Leonids by comet P/Temple-Tuttle, and the Geminids by 3200 Phaethon.
Though the major meteor showers can produce startling numbers of meteors, dust regularly passes into the Earth's atmosphere, and meteors can be seen on any clear night of the year. The background rate of dust entering the atmosphere visible from one location on Earth creates about 10—20 meteors per hour.The rate of meteor production for each shower also varies widely from year to year. Some years the smaller showers barely rise above the background rate, but in other years the rate of meteors can verge on frightening. Several showers recorded in the last couple of centuries have produced above 100,000 meteors per hour, reportedly lighting the sky and falling near the rate of a snowstorm. In addition to the main meteor showers of the year listed in the accompanying table, there are another 70 or so minor but regular showers each year.
The meteor showers are named for the part of the sky the fire trails seem to appear from: the Geminids, for example, appear to originate from the region of the constellation of Gemini, although of course that is an optical illusion (the dust is coming from space just outside the Earth's atmosphere and not from distant stars).
Large observatories—notably the radar observatory at the University of Canterbury in New Zealand and the IAU Meteor Data Center in Lund, Sweden—track meteors. By analyzing the paths of meteors in the
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