Astronomy Information Service
Perseid Meteor Shower - August 2008 Summary: There’s a meteor shower this summer that peaks on the night of August 12th-13th. Go out after 2AM that night to a dark location away from city lights, and you should see about 1 meteor every minute or two.
On any given night, skywatchers can expect to see several streaks of light flash across the sky and disappear. Often called "falling stars" or "shooting stars", these flashes appear in the blink of an eye and then disappear forever. But they're not stars…they're actually tiny pieces of interplanetary debris disintegrating high in Earth's atmosphere. These flashes of light are officially known as meteors. A meteor is caused when a speck of dust from outer space crashes into the Earth at high speed and burns up in the atmosphere due to friction. They can often be quite bright, outshining the stars and being easily visible to the unaided eye. What's In A Name? "Meteor" refers to the flash of light we see, not the piece of debris itself. If you want to talk about the actual object out in space, it's called a meteoroid. Larger meteoroids say, the size of a marble - are few and far between, and larger ones are even more rare. When one of these larger pieces enters the atmosphere, some of it might survive its fiery passage and actually hit the ground to become a meteorite. Why August? Space is littered with meteoroids somewhat randomly, so you can see a few of them on any night of the year if you happen to be looking up at the right time. There are a few areas in space, however, where meteoroids are more heavily concentrated: in the trails of comets, which spew out gas and dust as they orbit the sun. The orbit of a comet contains a dense cloud of meteoroids left behind by the comet's tail - sort of an interplanetary dust bunny. When the earth goes through the trail of dust, we see a lot
Manitoba Museum - Astronomy Information Service Updated July 28, 2008
more meteors than usual for a brief time. That's what will occur this August, as the Earth goes through the trail of dust left by Comet Swift-Tuttle. The Perseids The Perseid meteor shower has been known for thousands of years, but the comet which creates it wasn't discovered until 1862. Two amateur astronomers (Lewis Swift and Horace Tuttle) independently discovered it, and following astronomical tradition, the comet was named for them. The earth passes near Comet Swift-Tuttle's orbit around August 12 of each year, giving us a chance to see the Perseid meteor shower. The Perseids get their name not from their parent comet, but from the constellation which seems to be their source: the constellation Perseus the Hero. But you don't need to know the constellations or be able to find Perseus to see them. The name is really just a way to distinguish the more than three dozen annual meteor showers from each other. The meteors can be seen all across the sky with the unaided eye, if you go out at the right time. Where, When and How to Observe the Perseids This year, the Perseids peak on the morning of Wednesday, August 13, after the moon sets. You can observe before this time or even a few nights before, but you won’t see as many meteors. The shower builds uup to its peak, and the moon will make it hard to see the meteors that are there. From 2AM until dawn on the 13th you can expect between 40 and 100 meteors per hour from a dark site away from city lights Before you leave, pack your observing gear: a reclining lawn chair or blanket to lie on, your favorite mosquito defense, and some warm clothes (it gets chilly late at night when you're laying on the ground). Head as far from city lights as you can. If you can't leave the city, seek out a park or backyard where you are at least shielded from direct streetlights shining in your eyes. It is worth the trip to darker skies, though; the city lights will make it hard to see all but the brightest handful meteors. (It goes without saying that you shouldn't bring along any bright lights of your own to spoil the darkness. If you need light, bring along a dim flashlight with a red cover over the lense - red light doesn't ruin your night vision as quickly.) Set up your lawn chair or blanket with your feet pointing generally south (although the direction doesn't matter too much), and look high up in the sky. Get comfortable - you'll be sitting in one spot for a while. Sit back and keep your eyes open for the meteors as they appear roughly once every minute or so. They can appear anywhere in the sky, but if you trace backwards along their path they should all be "coming from" the constellations Perseus, which is low in the northeast. You may notice "clumps" of several meteors one after the other, and then a pause with no meteors. Good luck and clear skies! Σ
Manitoba Museum - Astronomy Information Service
Updated July 28, 2008