August 12, 2010 - Planets Align for the Perseid Meteor Shower

The show begins at sundown when Venus, Saturn, Mars and the crescent Moon pop out of the western twilight in tight conjunction. All four will fit within a circle about 10 degrees in diameter. No telescope is required to enjoy this naked-eye event.

The Perseid meteor shower is caused by debris from Comet Swift-Tuttle. Every 133 years the comet swings through the inner solar system and leaves behind a trail of dust and gravel. When Earth passes through the debris, specks of comet-stuff hit the atmosphere at 140,000 mph and disintegrate in flashes of light. These meteors are called Perseids because they fly out of the constellation Perseus.

2010 is a good year for Perseids because the Moon won't be up during the midnight-to-dawn hours of greatest activity. Lunar glare can wipe out a good meteor shower, but that won't be the case this time.

As Perseus rises and the night deepens, meteor rates will increase. For sheer numbers, the best time to look is during the darkest hours before dawn on Friday morning, Aug. 13th, when most observers will see dozens of Perseids per hour.

For best results, get away from city lights. The darkness of the countryside multiplies the visible meteor rate 3- to 10-fold. A good dark sky will even improve the planetary alignment, allowing faint Mars and Saturn to make their full contribution to the display.