The Perseid meteor shower appears to originate in the constellation Perseus. (Sky & Telescope )
The annual Perseid meteor shower begins late Friday night, with the peak occurring in the early hours of Sunday morning local time. The number of visible meteors is generally lower than during December's Geminid meteor shower, but the Perseids are frequently more observed because they occur during warmer weather and in a vacation month.
The shower gets its name because it appears to originate in the constellation Perseus, but the stars have nothing to do with it. Meteors are actually fine bits of dust that originate within our solar system. Meteor showers occur when the Earth passes through the dust belts. The Perseid meteor shower is caused by remnants of Comet Swift-Tuttle, which passed close to Earth in 1992, but won't approach closely again until 2125. The shower was particularly abundant in the years surrounding the comet's last close approach, but enough dust remains behind to give a good show.
Most of the observed meteors are sand-sized grains of dust, not large rocks. As they enter Earth's atmosphere at 134,000 mph, they compress air, creating a white-hot shock wave, which is visible from the ground.
The meteors are best observed in the darkest areas of the sky. Binoculars and telescopes don't help much because they restrict the field of view.
During the shower, NASA astronomer Bill Cooke and his team from NASA's Marshall Space Flight Center will be chatting about the showers and answering questions here.
For the record, 2:45 p.m. Aug. 10: An earlier version of this post said the meteor shower begins Saturday. It begins late Friday night.