Photograph by Jeffrey Berkes, Your Shot
Published August 10, 2012
The Perseid meteor shower peaks this weekend, and thanks to relatively dark skies, the 2012 edition of the annual sky show should be well suited to naked-eye stargazing.
Sky-watchers with backyard telescopes, though, might join NASA in training their lenses on the moon for an elusive, potentially flashy Perseid sideshow.
Peaking late Saturday night and before dawn Sunday this year, the Perseids occur when Earth and the moon pass through a cloud of rocky particles shed by comet Swift-Tuttle.
Hitting the atmosphere at speeds of almost a hundred thousand miles (160,000 kilometers) an hour, the meteoroids burn up, producing streaks of light—meteors, or shooting stars—each lasting just a fraction of a second.
In dark, cloudless areas, the first meteors should become visible around 10 p.m. local time, with rates increasing through the night, eventually reaching a rate of one or two shooting stars per minute before dawn.
The easiest way to spot the Perseids is to look for their namesake constellation, Perseus, which will rise above the local horizon in the northeastern sky around midnight. The meteors will appear to radiate, or shoot from, this spot. (See Perseid-viewing diagram.)
Observers in light-polluted suburbs should expect to see about half as many Perseids. (See light-pollution pictures of from National Geographic magazine.)
No matter where you are, glare from the waning crescent moon may obscure some of the fainter meteors a bit when it rises between 1 and 2 a.m. local time, but not enough to discourage stargazers from looking skyward—preferably with unaided eyes—for one of the year's best sky shows.
With the right telescope and a lot of patience, the pleasures of the Perseids can take on an extraterrestrial dimension.
On the moon, golf ball-size meteoroids will slam into the surface at up to 155,000 miles an hour (250,000 kilometers per hour), producing explosions that should each be equivalent to a few hundred pounds of TNT.
The lunar flashes last only a thirtieth of a second each—too brief for the human eye. But with video-equipped telescopes, backyard astronomers can record the moon explosions, seen as momentary flashes of light on the unlit portion of the moon's surface.
NASA astronomer Robert Suggs recommends at least an 8-inch (20-centimeter) telescope equipped with a digital video camera and recorder.
On average, amateur astronomers capture one or two flashes with this type of equipment, said Suggs, manager of NASA's Lunar Impact Monitoring Program at Marshall Spaceflight Center in Huntsville, Alabama.
Overall more than 200 lunar flashes are known to have been recorded by backyard telescopes since 2005, when NASA began keeping track. (Take a Perseid meteor shower quiz.)
The space agency uses the backyard-telescope data as part of its effort to determine lunar meteor sizes and strike rates—data that could help prepare for potential long-term manned missions to the moon.
(See Perseid pictures.)
Geminids Next Big Chance to See Moon Meteors
This year, the densest part of the Perseid meteor shower will hit the far side of the moon, beyond human vision and earthbound telescopes.
A few Perseids, though, "should be spilling over to the northern portion of the near side of the moon," Suggs said. NASA "will be doing lunar observations this weekend but don't expect to see many Perseids," he added.
If you miss out this time, your next best opportunity to see lunar flashes will be during the annual Geminid meteor shower in mid-December, Suggs said. (See "Pictures: Brilliant Geminid Meteors Dazzle Sky-Watchers.")
During the 2012 Geminids, 90 percent of the moon's unlit surface will be in the path of the meteor shower—making this year's Geminid lunar flashes highly visible from Earth.
Andrew Fazekas is the astronomy columnist for the Montreal Gazette, past president of the Montreal chapter of the Royal Astronomical Society of Canada, and a frequent contributor to National Geographic News.
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