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Why This Year’s Perseid Meteor Shower Promises to Be Especially Dazzling

Thanks to the moon’s conspicuous absence, those looking up at peak viewing hours will see 60-70 shooting stars every hour

A view of the Perseid meteor shower over Northern Ireland in 2017. (Sean Harkin / Alamy Stock Photo)
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If stargazing had a Billboard Hot 100 chart, the Perseids would be the Beatles. But while the Perseid meteor shower always knows how to put on a show, NASA meteor expert Bill Cooke recently told Sarah Lewin of Space.com that this year, the Perseids will be treating viewers to, essentially, Liverpool Cavern Club-caliber performances.

In part, astronomers can thank a fortuitously timed moon cycle that will leave the skies darker than usual. When the Perseids peak this weekend, they will offer crisp views of about 60-70 shooting stars every hour. While the best time to catch them in the act will likely be late into the evenings of August 11 and 12, Cooke tells Lewin, some speckles will be visible as early as August 9.

In no uncertain terms, all meteor showers are defined by a single journey: our own planet casually slogging through the path of a comet’s or asteroid’s fiery pebble poops (OK, debris). As these space rocks streak through the sky, they shed bits of dirty dandruff as they are warmed by the sun. The newly liberated meteors—often no bigger than grains of sand—are set ablaze as they hurtle through the atmosphere. But here on Earth, one comet’s trash is another human’s treasure.

During the Perseids, Earth is moseying through the trail dust of a comet named Swift-Tuttle. The comet, measuring 16 miles across, blitzes by Earth every 130 or so years, going about 36 miles per second (that’s 150 times faster than sound). At this size and speed, Swift-Tuttle would do some serious damage if it were, to say, ever strike the Earth. (The late astronomer Brian Marsden once predicted that ominous forecast for the year 2126—though his portentous prophecy has since been retracted.) But we’re in no such danger in 2018, when Earth rides Swift-Tuttle’s coattails from July 17 to August 24. The month-long drive-by will place Earth in the densest debris on August 12—the ideal time to gaze skyward.

This year's Perseids coincide with a new moon, meaning the moon will rise and set with the sun so there will be no moonlight to outshine the meteors. A new moon kicks off the lunar cycle. As the moon waxes, it rises and sets later in the day until it’s all grown up: a full moon operating on a schedule opposite of the sun’s.

This is great news for shower-chasers: As the moon shows only a sliver of its face in the days following the new moon, when the Perseids are at their peak, it will still set before midnight, clearing the stage like the perfect opening act before the meteoric main event.

Also showing their faces this weekend will be Venus and Jupiter—though like the moon, they will exit stage left before the Perseids are fully underway. However, Mars and Saturn will both make special guest appearances during the meteor shower’s zenith.

The Perseid meteor shower will be most visible in the Northern hemisphere—and the more of a night owl you are, the more likely you are to glimpse the comet dust, best viewed after 2 a.m. local time. Urban dwellers may be out of luck, though, due to light pollution.

To fully take in the show, Lewin of Space.com recommends giving your eyes at least 30 minutes to adjust to the darkness before peering into the skies—and settling in with patience. But if Cooke is correct, and the stars have aligned, the wait will be worth it to see the show of the year.

Editor's note, 8/8/18: This piece has been corrected to reflect the Swift-Tuttle comet's rate of travel is around 150 times faster than the speed of sound, not light.

About Katherine J. Wu
Katherine J. Wu

Katherine J. Wu is a PhD student in Microbiology and Immunobiology at Harvard University and Co-Director Emeritus of Science in the News, a graduate student organization that trains young scientists to communicate science to the general public. She is also a 2018 AAAS Mass Media Fellow at Smithsonian magazine. Website: katherinejwu.com

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