The Perseid meteor shower promises about 70 shooting stars an hour this year and peaks on Aug. 11-12. / Christophe Lehenaff/Getty Images/Photononstop RM
Summertime, and the shooting stars are easy. Just pack a lawn chair and save yourself a few hours long past bedtime for the watch party.
Here comes the Perseid meteor shower, which promises about 70 shooting stars an hour this year and peaks on Aug. 11-12. Appearing every August, the meteors take their name from their apparent origin in the constellation Perseus, the hero of ancient Greek myth born from a shower of heavenly gold.
“The Perseids are the good ones,” says meteorite expert Bill Cooke of NASA’s Marshall Space Flight Center in Huntsville, Ala. Known for producing fireballs that might streak across a third of the sky, the Perseids owe their brilliance to the speed — nearly 134,000 mph — with which they smack into the upper atmosphere. “It’s also because of the size of the meteors,” Cooke says — dust grains about one-fifth of an inch across that burn nicely as they zip overhead.
Those dust grains come courtesy of Comet Swift-Tuttle, which circles the sun once every 133 years and leaves behind a debris trail. (Comets are basically dirty snowballs that develop tails when they approach the sun and start to melt. Different ones are responsible for other regular meteor showers, such as April’s Lyrids brought by Comet C/1861 G1 Thatcher, and November’s Leonids brought by Comet 55P/Tempel-Tuttle).
You will have to stay up late to see the Perseids at their peak; the best viewing comes from midnight to dawn, particularly after the half-full moon sets at 1 a.m. on Aug. 12, says Astronomy magazine’s Michael Bakich. But they should appear nights in the week before and after the peak, as well.
“Get out of the city and the lights to give yourself a chance to see them,” he says. The rule of thumb is that you should be able to see all the stars of the Big Dipper — seven stars if you are counting — to give yourself enough darkness to catch the shooting stars. And give your eyes an hour to adjust.
“There will be a dozen ‘ooh’ moments in that hour,” Bakich says. “Ones when everyone will say, ‘Did you see that?’”
Although the shooting stars seem to come from the constellation Perseus, don’t look there to see them, Bakich advises. Instead, look about one-third of the sky down and away from the constellation to spot meteors streaking across the sky. “That makes them easier to pick out,” he says.
While you are enjoying the sky show, satellite operators are buttoning up spacecraft to protect them from the onslaught of comet dust, says Cooke, who prepares meteor shower forecasts each year for space businesses. The Hubble Space Telescope might point the opening to its mirrors away from the direction of the shooting stars, for example, and other satellites might turn antennas away from the shower.
All of the comet-inspired skywatching this summer is a warm-up for the big sky show later this year, the approach of Comet ISON, which will come within 700,000 miles of the sun. That’s 124 times closer than Earth approaches. The comet may blaze into view as the “Comet of the Century” (as one NASA news release put it) after its closest approach to the sun Nov. 28.
“I think it will be spectacular,” Bakich says. The comet comes from a family of space snowballs known for the brightness of their tails, he adds, and its orbit suggests it may be fresh from the comet belt, with more material to burn as it passes by the sun. The closest it will come to Earth is a comfortable 40 million miles away in December on its way back.
“We might even be able to see it in daylight,” Bakich says. If so, the comet will be visible for months and pass right over the North Pole, making it a viewing treat for the Northern Hemisphere for much of the winter.
Other folks aren’t so certain the comet will be that bright, even after its grazing pass by the sun.
“That event is likely to make it sprout a long tail that will show pretty well in the first two weeks of December as the comet climbs the dark eastern sky before dawn,” says Sky & Telescope senior editor Alan MacRobert. “Set your alarm clock.”
Cooke believes the comet will break up when it gets close to the sun, disappointing everyone who hopes for a sky show. He points to 1973’s Comet Kohoutek, another would-be Comet of the Century that partly broke up on approach to the sun and failed to impress. “It didn’t even come as close to the sun as Comet ISON will and it broke up,” he says.
Instead, Cooke is putting his money on the Perseids for the year’s best skywatching. NASA will publish a Web chat of his observations of the meteor shower at nasa.gov/topics/solarsystem/features/ watchtheskies for anyone who wants an expert opinion.
Says Cooke, “All you need is to lie flat on your back, and the reward is meteors.”