Spectacular Perseid meteor shower tonight

Dark Nights for This Year’s Perseids
Mark your calendar for Sunday night, August 12-13
By ALAN MACROBERT
Posted: 2007-08-11 16:48:28

This year the new moon of August comes on Sunday, the 12th, perfectly timed to bring dark, moonless nights around the peak of the Perseid meteor shower. Moreover, Earth should pass through the shower’s richest part around 1AM ET on August 13th — so North Americans and western Europeans should have the best seats in the house.

The Perseids are bits of space debris that were shed by Comet Swift-Tuttle in past centuries and remain traveling more or less along the comet’s 130-year orbit around the sun. The particles range in size from sand grains to pebbles, and they have the consistency of dry dirt. As it orbits the sun, Earth passes through this thin “river of rubble” every year in mid-August. Each meteoroid rips into our upper atmosphere at 37 miles per second, creating an incandescent trail of shocked, ionized air. This hot trail, not the tiny meteoroid itself, is what you see.

The Perseids are one of the two strongest, most dependable annual meteor showers (the Geminids of December are the other; here’s a list of all the best ones). The grand Perseid displays of the 1990s seem to be well and truly over, so this year under a dark sky you might see “only” 60 to 90 Perseids per hour between midnight and dawn. Light pollution cuts down the numbers, but the most spectacular streakers always shine through.

Here is the full article.