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See (and hear) the meteor show

When the late show is over, turn off the TV, step outside and catch a late, late show in the night sky. It's prime time for the Perseids, arguably the most accessible meteor shower of the year.

"If you want comfort, this is the shower to see," said Bill Cooke, the head of NASA's Meteoroid Environment Office at Marshall Space Flight Center in Alabama.

Every night, Cooke has been turning on a couple of all-sky cameras in Alabama and Georgia to catch meteor trails as they streak through the sky. This year's been a great one for the Perseids, in large part because the moon doesn't glare in the sky when the show is getting good.

The absolute best viewing is expected Thursday night - actually, between midnight Thursday and dawn on Friday. Perseid meteors should be visible every night from now until next week. At its peak, observers could see at least one meteor every minute, Cooke told me. You just have to know where and when to look - and the experience goes much more smoothly if you make a few preparations.

First, some basic facts about meteors: As explained in our interactive graphic, meteor showers occur when our planet plows through a trail of space grit left behind by a comet. Those bits of grit zip through the upper atmosphere at speeds of more than 125,000 miles per hour, lighting up a trail of ionized air.

Don't worry: There's virtually no risk of being hit by one of these falling stars. Most of this grit burns up dozens of miles above us. A week ago, Cooke's camera in Alabama snapped a picture of a fireball lighting up the sky much more brightly than any planet - and even that sparkler self-destructed at an altitude of about 56 miles.



An all-sky camera captures a fireball streaking over Alabama on Aug. 3 during the Perseid meteor shower.

The Perseids are produced by trails of grit left behind by Comet Swift-Tuttle during its 133-year orbit. Earth starts plowing through the Swift-Tuttle debris in late July, and the height of the shower comes annually around Aug. 12-13. The Perseids are so named because they appear to emanate from a point in the constellation Perseus, also known as a "radiant." Because the radiant is in northern skies, Northern Hemisphere observers are in a more favorable position to see the shower.

The strength of the shower varies from year to year, depending on what part of Swift-Tuttle's debris trail our planet moves through. Based on what he's seen so far, Cooke expects a "very good Perseid shower this year."

The good news is that Cooke is making himself available on Thursday to discuss the shower via this NASA chat page. He'll be taking questions during the afternoon, starting at 3 p.m. ET, and then he'll be back online from 11 p.m. ET to 5 a.m. ET Friday. The bad news is that all this Internet chatting will seriously cut into his own meteor-watching time.

"I'll be in the press room with no view of the sky," he said.

Perseid radiant


Perseid meteors appear to emanate from a point in the constellation Perseus, as shown in this graphic depicting the northeastern sky at around midnight. Although the meteors can appear in any part of the sky, their tails can be traced back to that point..

A couple of years ago, I put together a top-ten list of tips for maximizing your meteor-watching experience. Here's an updated game plan for making the most of the meteors, assembled with Cooke's help:

  1. Pick a viewing spot far away from city lights, where the skies are likely to be clear and wide-open. Higher elevations are usually better than lower elevations, and you don't want to be surrounded by trees, buildings or other obstacles to viewing.
  2. For help in site selection, you can check out the Clear Sky Chart website, which provides weather conditions for skywatching ... and links to popular viewing locations on a state-by-state basis. Your local astronomy club can also point you in the right direction. This year, some events for amateur astronomers are timed to take advantage of the Perseids - for example, star parties in California's Mojave Desert, in Michigan, in Oregon and Washington state.
  3. Bring a blanket or a chaise lounge to lie back on. Have layers of clothing available in case the air turns chilly at night. Bring snacks or drinks. Bring a flashlight so you can find your way through the dark. Bring a music player or radio if you need a diversion. And bring your friends. Meteor-watching sets a great mood for chatting about cosmic issues, or meditating on the wonders of the heavens.
  4. Don't give up too quickly. Give your eyes plenty of time to get accustomed to the dark. Although the meteors appear to emanate from the radiant in Perseus, don't focus exclusively on that point. "The closer the meteor is to the radiant, the shorter the trail is," Cooke explained. "I always tell people to look straight up, because that way, they'll catch plenty of meteors far enough from the radiant to see a trail."
  5. The later you can stay up, the better. "It's a late-night shower," Cooke said. You could start seeing Perseids at around 9:30 p.m., and those "Earth-grazers" tend to leave the longest, most impressive trails. But the show doesn't get good until after midnight, and the peak usually comes just before morning twilight begins.
  6. To get a better sense of what to expect at which time, use NASA's Fluxtimator. When you click in the right coordinates for meteor shower, date, location and viewing conditions, the Java-based calculator charts what the estimated meteor flux will be at different times.
  7. If you're totally clouded out, you can try listening to the meteors. NASA's Perseid Web page includes a video feed that shows what Cooke's cameras are seeing, accompanied by a soundtrack of radio blips created by the meteor streaks. Cooke said it's also possible to hear the radio blips by tuning your FM radio to a station so distant that all you can hear is the hiss of a carrier wave. "When a meteor passes, you'll hear a blip kind of like a sonar blip," Cooke said. Here's a spooky audio file that gives you an idea what the radio echoes sound like. SpaceWeather Radio also lets you hear the meteors, and you can always check out the Perseid Fireball Cam.
  8. The meteors aren't the only game in town: Saturn, Mars and Venus form a striking planetary triangle in western skies just after sunset, and the International Space Station is visible from many North American locations just before sunrise. Impress your friends by telling them that the bright star near the zenith at around 11 p.m. is Vega (made famous by the "Contact" movie). and that the bright "star" in the southeast is the planet Jupiter. If you're far enough north (or south), you might even see an aurora.
  9. If you want to share your meteor sightings with the world via Twitter - and find out where the sightings are sizzling - the MeteorWatch website is the place for you.
  10. Even if you miss the meteor shower completely, you can click through SpaceWeather.com's meteor gallery and catch up on the highlights. And you can start making plans for the Leonid meteor shower (peaking Nov. 17-18, unfortunately during a nearly full moon) as well as the Geminid meteor shower (peaking Dec. 13-14).

Cooke noted that December's Geminids are the equal of August's Perseids, based on the number of meteors you should be able to see. "But nobody likes to freeze their backside," he added. Which gets back to the comfort angle.

Whatever you do, don't obsess over how many meteors you're seeing (or not seeing) per hour. The Perseids are a good excuse to get outside in the summer, experience nature's wonders and then share those experiences. Last night, for example, I saw exactly one meteor from my viewing spot, a half-hour's drive outside Seattle. One meteor! But I also saw mountain vistas, a deer with magnificent antlers lurking by the side of a forest road, and the Milky Way in all its glory. Even setting aside the meteor, it was well worth the trip.

That's my experience. What's yours? Feel free to share your stories of skywatching adventures past and present in the comment space below.

More Perseid guides on the Web:

For more about the Perseids, check out this posting from last week. If you have some Perseid pictures that you're proud of, share them using our FirstPerson photo in-box. Join the Cosmic Log corps by signing up as my Facebook friend or hooking up on Twitter with @b0yle. And if you really want to be friendly, ask me about "The Case for Pluto."