Kicking off what's become an annual ritual for many stargazers, the Perseid meteor shower is set to peak tomorrow night with its dazzling flurry of shooting stars. (See Perseid pictures.)
Peaking late Friday through early Saturday, this year's cosmic fireworks will be somewhat dampened by the glare of a full moon. But the Perseids can still offer a crowd-pleasing sight for many people worldwide.
"The Perseids are almost always a really good show, with usually on average about 50 to 60 meteors an hour during the peak," said Jim Todd, staff astronomer and planetarium manager at the Oregon Museum of Science and Industry in Portland.
"This year, while the moon will wash out some of the more dim meteors, we should still get a good show with around 10 to 20 meteors an hour."
Perseids Born of Comet Leftovers
In general, meteors are produced when small dust grains from space impact Earth's atmosphere at high speeds.
"The streak of light we see is this debris burning up because of friction with the atmosphere," Todd said.
Trickles of wayward meteors are visible year-round in any clear night sky. A meteor shower happens when bunches of them fall over a few particular nights of the year.
In the case of the Perseids, Earth regularly slams into leftover pieces from the comet Swift-Tuttle, plowing through the debris trail at 150,000 miles (241,402 kilometers) an hour.
(Take a Perseid meteor shower quiz.)
The planet hits this orbiting debris stream around the same time every year, and the dust cloud is consistently thick enough to put on an impressive sky show.
How to See Perseids Despite Full Moon
As with other annual meteor showers, the Perseids are named after the constellation from which they appear to radiate—in this case, the constellation Perseus.
In the coming nights Perseus will rise above the northeastern horizon. To see the full effect of the meteor shower even with the lunar washout, Todd suggests heading to areas free from light pollution and facing toward Perseus.
"Your best chance for spotting the meteors will be to move away from the urban city lights and view meteors in dark rural locations in the early morning hours, when the radiant is highest in your local sky," he said.
Todd also suggests going out on any clear night immediately before or after the peak, when up to a couple dozen shooting stars an hour may be visible.
(Also see "'Spectacular' Double Meteor Shower This Week" [July 25, 2011].)
Already sky-watchers around the world are reporting an average of 10 to 15 Perseids an hour, including surges of activity featuring brighter-than-average meteors called fireballs racing across the the sky.
"If you don't see any meteors for a while, don't be discouraged," Todd said. "It's important to remember that sometimes meteors come in dramatic bursts rather than steadily throughout the night."