Moon steals thunder of 2011 Perseid shower

The Perseid meteor shower is August's trademark astronomical event and one of the top annual celestial events to observe.

The shower peaks during the early morning hours of Aug. 12 and 13 and can feature up to 60 meteors an hour. Stray Perseid meteors have been spotted from July 23 to Aug. 22.

The shower's radiant point - the area from where the meteors originate - is in the constellation Perseus. The full moon's glare will hide fainter meteors this year, but with a possible average of a meteor or two a minute, it could still be a memorable sight. For prime viewing, get as far from light pollution as you can and look to the northeast after midnight.

These meteors tend to be bright and fast and will increase in number as midnight approaches, with the most meteors appearing in the hours before dawn. These meteors frequently leave smoke trails as they burn up in the atmosphere.

The Perseid meteor shower has been observed for about 2,000 years, with the earliest records coming from the Far East. Its name comes from the word "Perseides," a Greek mythological term referring to the descendants of Perseus the Hero.

The stream of debris that causes the shower is called the Perseid cloud and stretches along the 130-year orbit of the comet Swift-Tuttle. Most of the dust in the cloud was deposited by Swift-Tuttle about 1,000 years ago, but there is also a relatively new deposit of dust that was burned off the comet in 1862 as it approached the sun. When Earth passes through that deposit, the shower is much more active.

Perseid meteors can be seen across the entire sky, but the path of Swift-Tuttle's orbit means meteors are mainly visible in the northern hemisphere. As with all showers, the rate of meteors is highest during pre-dawn hours because the Earth comes in contact with more debris as it turns toward the sun.

Start watching for the Perseids this week as they build toward their peak. By the second week of August, the waxing moon will start to overtake the sky between midnight and dawn, so try to catch as many meteors as you can before the full moon moves in.