Student Features

It's Raining Rocks in Space!
08.05.04
Tell Orion and the other constellations to get out their umbrellas. They are in for a shower -- a meteor shower, that is. It's raining rocks in space! The annual Perseid (purr see id) meteor shower has arrived. And, it could be unusually good.

The shower began, gently, in mid-July. This was when Earth entered the edge of a cloud of dust from Comet Swift-Tuttle. Dust-sized meteoroids hitting the atmosphere will streak across the night sky. This will be what many people call "falling stars" or "shooting stars." At first, there was only a sprinkling of meteoroids, just a few each night, but the rate will build.

What's the difference between an -oid, -or and an -ite?

So what's the difference between a meteoroid, meteor and meteorite? A meteoroid is just a chunk of rock in space. They are usually less than 10 meters (33 feet) wide. A meteor, or shooting star, is a streak of light that is caused by the friction when a meteoroid from space enters the Earth's atmosphere. And, meteorites are the leftovers that survive the friction of the atmosphere and land on Earth.
Perseid meteor shower streaking through the night sky full of stars


Image to right: This Perseid was caught streaking through the Milky Way in 2001. Credit: NASA/Nathalie Dautel

You may see a meteor streak through the sky on any night. But, when Earth enters the orbit of a cluster of meteoroids, we have what we call a meteor shower. Every summer during July and August, Earth enters the orbit of the Perseid meteoroid cloud. This cloud was left by the Comet Swift-Tuttle. But this year will be a great year to see the shower.

When and where should I look to see the shower?

The middle of August should be the best time to view the shower. There are two reasons for a good sighting during this time.
  1. There will be a cloud of pieces of dust that will be very close together. On August 11 and 12, this cloud will drift across Earth's orbit. That will mean more meteoroids to see. You may see from dozens to hundreds of meteors per hour.
  2. On August 15, there will be a new Moon. Remember that a new Moon is when you cannot see the Moon at all. That means that there will be no moonlight to light up the sky. You will see more when the sky is dark.
This shower got its name because its starting point, or radiant, is the constellation Perseus. (Skywatchers who are south of the equator will not be able to see this constellation well.) Perseid comes from Perseus.

The best time to look for these Perseids is during the hours before dawn on Thursday, August 12. Set your alarm for 2 a.m., go outside, and lie down on a sleeping bag with your toes pointed northeast. You'll soon see meteors racing along the Milky Way.
 
Skymap showing the pre-dawn sky on Aug. 12th.
Image above: The pre-dawn sky on August 12. The Perseid radiant is a red dot. While you're looking for meteors, check out Venus, Saturn and the crescent Moon, too, near the horizon. Credit: NASA


Can't Wake Up at 2 a.m.?

Try looking around 9 or 10 p.m. on Wednesday, August 11 when Perseus is hanging low in the eastern sky. You won't see many meteors then, but the ones you do see could be memorable.

See cool Perseid pictures:

A Perseid Aurora
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Rainbow Perseid
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Island Universe, Cosmic Sand
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Adapted from The 2004 Perseid Meteor Shower