Meteors!

There's a truly gnarly show this Sunday night (Aug. 11). It starts kind of late, and it's kind of long. But it's rated G, and you can see it from your backyard.

You could call the show "The Night of the Perseids." It stars hundreds of tiny actors that have a brilliant, if meteoric, career. It's really called the Perseid meteor shower. You'll be able to see these "shooting stars" (weather permitting) when it gets dark, after about 10 p.m. The show really gets good after midnight!

What's more, you could become the "eyes" for astronomers studying meteors. If you watch for at least an hour, record what you see, and send the information to the e-mail address at the end of this article, your data could help update a reference book used to calculate the meteors' orbits.

Perseid meteors are leftovers from Comet Swift-Tuttle, which orbits the sun every 130 years. Swift-Tuttle came by four years ago, leaving more debris behind. Since the comet's orbit crosses that of Earth, our planet plows through these leftovers like clockwork each August.

So your parents say, "OK, you can watch the show." What do you do? Dress warmly and take food and something to drink with you, if you want to watch for more than a few minutes. The best way to view a meteor shower is to lie on your back. This way, you can see the most sky at once. Use a beach lounger or a sleeping-bag pad to be comfortable.

Find the biggest patch of sky you can. Look for an open field, for example, or a hilltop with a good view facing north. The best spots are places where treetops or buildings are less than four or five hand-widths high when you hold your hands at arms' length. If you live near a city, get as far away from the glow of city lights as you can. The darker the sky, the more meteors you'll see, because many of them are faint.

Once you get outside, don't look at any bright lights. It takes about 20 minutes for your eyes to adjust to the dark. And to see fainter meteors, you want them to stay adjusted.

Other things you'll need if you want to record what you see:

*A small flashlight with red cellophane across the front. Use this to read star charts or find things you bring. The red light won't dull the "night" vision it took you 20 minutes to develop.

*A tape recorder, so you don't have to write anything while you are watching the sky. You can just speak into the microphone.

*A digital watch with a timer that can count down, beep, and count down again without stopping.

*A camera, if you want to try to photograph meteors. The camera must be able to take time exposures of up to 20 minutes. Use a tripod to hold the camera steady. Turn the camera to the southwest, then point it nearly straight up (about 80 degrees from horizontal). A normal lens (50 mm) focused on infinity, along with a film like Kodak's Tri-X 400 (a high-speed black-and-white film), should give you some interesting shots.

TRY a variety of exposures; two minutes may suffice as the meteors become more frequent. (If you get some good photos, send them in! We'll consider printing them. Our address is: The Christian Science Monitor, Home Forum Page, One Norway St., Boston, MA 02115. Include your address and phone number.)

Mark Davis, who takes reports from meteor-watchers for the North American Meteor Network, says that his group only needs some basic information to make use of your sightings:

1. How dark the sky is. To estimate this, find Polaris, the North Star, and see how many other stars you can spot in the Little Dipper. Make a note of the faintest one you can see and where it lies in the constellation. Later, when you write down your data, you can use a sky chart or other reference to look up and report that star's brightness (magnitude), which is expressed as a number. The brightness of the faintest star you see is the "limiting magnitude" of the sky. Mr. Davis says it's a good idea to check and record the sky's limiting magnitude every 30 minutes.

2. The time you begin and end your observations. Once your eyes have adjusted to the dark and you're ready to begin, take a peek at your watch with your red-cellophane-covered flashlight and speak the time into your tape recorder. Now start the countdown timer on your watch to beep every 10 minutes.

3. The times you see a meteor. Note on the tape each time you spot a meteor: "There's one!" Be sure your tape recorder is also recording the beeps of your watch. (Wise viewers will run a short test first.)

3. Whether the meteor is a Perseid or not. If an imaginary line along a meteor's trail can be traced to a spot near the constellation Perseus (see the star chart on the facing page), it's a Perseid. Otherwise, it's a non-Perseid. The easiest way to record this is to say "Perseid" or "non-Perseid" each time you see a meteor.

4. Your location, as specifically as possible. The best information would be your latitude and longitude, but the nearest town name will do. Depending on your location, the time, and the sky's darkness, you could see from 20 to 90 meteors an hour - about one every 3 minutes to one every 30 seconds.

Later, with an adult's help if needed, you can replay your tape and - ideally - figure out the time you saw each meteor and whether it was a Perseid. Again, be sure to include the location of your observing site, the date and time you were observing, and the sky's limiting magnitude (as well as any changes in it during the evening).

Once you have recorded all this information (don't forget to note your name and address), send it via e-mail to Mark Davis, who lives in Awendaw, S.C., at:

MeteorObs@Charleston.Net

Clear skies!

Questions or comments? The author's e-mail address is:

70741.462@compuserve.com