MAKE A WISH!! It's a shooting starThe Perseid meteor shower will be at its peak this year (2001) on August 12th, where an average of 80 shooting stars per hour should be visible to the naked eye. It isn't a one night event, however. The show began July 23, will build in number of meteors observable until the 12th, then will wind down, ending officially on August 22. The best way to observe the Perseids is to lie outside, in an area unaffected by city lights with your feet pointed away from the moon. Some watchers even prefer to watch from the shadow of a building or tree, to help block out the moonlight. Look straight up. The area where the meteor shower will be coming from is actually to the north/northeast, but meteors directly in front of you won't appear to move much and might be missed. Anytime after 10pm is suitable, but the best viewing is between midnight and dawn each night. This year, however, we have a slight problem...the moon. The moon will be full August 4th, and will continue to appear in the night sky after midnight, although it will be losing brightness. What that means to hopeful meteor watchers is that the moon will be up during the best time to watch. Some savvy star watchers will begin watching for the Perseids as early as August 2 and 3rd in the hours before dawn, after the moon has set. Also, on the night of the peak, the moon doesn't rise until 1 a.m. so that might be a window to watch for as well. Another benefit of watching early this year, is that the Delta Aquarid meteor shower is going on now as well. It's a more rambling shower, with a less defined duration and expected number of shooting stars, but it is a decent show as well.
The Perseids are known for having a high percentage of meteors with visible "trains". A train on a meteor is a tail that lingers longer than the usual 1 or 2 seconds. Because of this, and because the Perseids have been commonly known to have a showing of over 200 shooting stars per hour, this is the most viewed of all meteor showers. Last year, (2000) the show was exceptionally good for many viewers across the United States and much of Canada. Just as hopeful observers were settling in for a long spell of meteor watching, the sky erupted in color. A billion-ton cloud of electrified gas from the Sun (a "coronal mass ejection") had crashed into Earth's magnetic field and ignited widespread auroras. All across North America sheets of red and green and purple light danced across the sky, stunning onlookers. As we are in a period of high solar activity, that could happen again. People who saw this display said it was the best they'd ever seen. We can only hope.
The Perseid Shower is named for the constellation Perseus which is where the meteors seem to start their path across the sky. Perseus is in the north/northeast sky, near the more familiar W shape of Cassiopeia. The shower is caused by the earth crossing the path of the tail of
Comet Swift-Tuttle. The comet swings by the Sun at 135 year intervals and leaves behind a trail of dusty debris. Its dust particles strike Earth's atmosphere traveling 59 km/s (132,000 mph). Their extreme speed is the reason that tiny comet particles, most no larger than grains of sand, can produce such dazzling streaks of light. Typical dust specks burn up entirely about 100 km above our planet's surface.
Note: The July 23, 2001 fireball observed in much of the Northeastern United States was not an early-arriving Perseid meteor, but rather a small solitary asteroid that probably had nothing to do with comet Swift-Tuttle.