Perseid meteors partially washed out by the gibbous Moon

For more information on this meteor shower, including a detailed sky chart
see August’s Skywatchers’ Guide.

The Perseid meteors become visible as the radiant (the path where the meteors seem to originate) rises (click to enlarge).

The annual Perseid meteor shower, one of the best meteor showers of the year (and the one everyone likes to see), peaks on the nights of August 11-12, 12-13 and 13-14. Perseid meteors can also be seen for the few nights before August 12 and after August 15, but in much reduced numbers.

The best times for highest rates of meteors are predicted to be on the morning of August 12, and the night of August 12-13. This year, the shower is partially washed out by the gibbous Moon that will rise at 10:40 p.m. on the peak evening of August 12, and by 11:25 p.m. on August 13. The large moon this year will brighten the sky in the late night hours, reducing the amount of shooting stars novice stargazers can see in moon-lit skies to maybe 10 or 20 shooting stars an hour from a dark sky location overhead. However, if clear weather is available then look for one of the year’s best annual sky shows starting soon after sunset. If monsoon clouds interfere, viewers will also be able to see meteors in numbers on the nights of August 11th-12th and August 14th-15th, some before the Moon rises, but more in the late night hours when the constellation Perseus (from which the shower is named) is high overhead.

Meteor watchers should seek out a dark sky several miles away from city lights and look high in the eastern and northern sky and overhead after the moon sets. To see the shower well, observers should view in the hours after sunset and before moonrise, far away from city lights. Good locations for viewing include the east end of Speedway at Saguaro National Park East or areas far west of Tucson such as the Tucson mountains and Saguaro National Park West. Observers should expect to drive 30 minutes to out of town, away from city lights, to get good views of the shower. Clear dark sky views without moonlight may reveal upwards of 40 to 50 meteors an hour. Again bright meteors will still be seen through the moonlight, but in much diminished numbers. Meteor watchers should scan the skies to the east, north and overhead. All that’s needed to see the shower are clear skies and a lawn chair.

The next major meteor shower for casual observers, that is visible without interference from moonlight, is the Geminid shower in December (usually peaking on December 13-14 each year). In addition, as in 2006, there’s always the possibility of seeing an Earthgrazing meteor. The best chance to see an Earthgrazing meteor will start near the end of evening twilight (or starting around 8:30 p.m.). For more information on the meteor shower, and Earthgrazing Perseid meteors, see NASA’s news story for 2009.

Causing the Perseid meteor shower is debris from a comet which last passed Earth in 1992 named Comet Swift-Tuttle. The debris consists of tiny particles of rock, some thinner than a hair and most no larger than a grain of sand. Nearly all the particles of a meteor shower burn up in Earth’s atmosphere. Comets are the source of nearly all meteor showers. Comets are bodies, often potato shaped and less than 6 miles in diameter, made of a loose aggregate of rock and ice that is in orbit around the Sun. As comets come in close to the Sun, they begin to evaporate off dust particles, gases and water vapor, leaving a long tail behind them. This tail leaves a trail of tiny debris in space, which Earth can pass through, resulting in a meteor shower.