Shower of Shooting Stars

<sup>A shooting star from the Perseid meteor shower.

Image Credit: Trond Erik Hillestad/Norwegian Astronomical Society</sup>

A shooting star is a small speck of interplanetary dust that enters the earth's atmosphere at high speed. Friction with the air causes the dust particle to heat up and glow. From the ground we see it at night as a streak of light, or shooting star, as illustrated in the above image.

One source of interplanetary dust is comets. As a comet passes close to the sun, ices start to evaporate from its surface. This frees chunks of rocks, dust, and gases. The solar wind spreads the dust and gas into the familiar comet tail. Every year, the earth passes through several dusty interplanetary trails created by comets. The appearance of shooting stars then rises dramatically. This is called a meteor shower. During the peak of a meteor shower, you may see several shooting stars every few minutes, although sometimes the count rate is much greater. The above image is a photograph of a shooting star from the Perseid meteor shower.

The Perseid meteor shower occurs every year between late July and mid August. This year it will peak on the nights of August 11-12 and 12-13. The Perseid meteor shower is so named because it is visible in the direction of the constellation Perseus. The Perseid shower is the result of dust released from comet Swift-Tuttle.

Other annual meteor showers:

More Cool Sites

For information on meteor showers and comets, visit the Everyday Classroom Tools project of the Smithsonian Astrophysical Observatory. Click on "Hands-on Astronomy," then on "Table of Contents," and, finally, on "Chapter 5: Planetesimals":

http://hea-www.harvard.edu/ECT/

We found the above image on a Web site of the Meteor Section of the Norwegian Astronomical Society:

http://www.stud.unit.no/~ltheen/meteor/

The Dutch Meteor Society has an entire page about predicting the date and time for the 1996 Perseid peak:

http://www.pi.net/~terkuile/meteors/dms-www/per961ml.htm

For more information on meteorites try the Web site of the Students for the Exploration and Development of Space (SEDS) at the University of Arizona:

http://www.seds.org/nineplanets/nineplanets/meteorites.html

Check out other observations in the Observation of the Week Archive.