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The Perseid meteor shower is at its best tonight. Unfortunately, that's not much to get excited about. The Moon is almost full, so its beautiful but pesky light will overpower the "shooting stars." Only a handful will shine through.
The Perseids occur every August as Earth flies through the orbital path of Comet Swift-Tuttle. The comet is a ball of frozen water and gases mixed with bits of rock and metal. As it approaches the Sun, some of its ices vaporize. That releases some of the solid particles, called comet dust.
When Earth flies through the comet's trail around the Sun, some of the dust grains slam into the atmosphere at tens of thousands of miles per hour. They vaporize instantly, creating streaks of light across the night sky.
Swift-Tuttle returned to the inner solar system almost two decades ago -- its first appearance since the Civil War -- so the Perseids were especially good through most of the 1990s. In recent years, though, they've dwindled by quite a bit. Instead of thousands of meteors, the shower's peak might produce just a few dozen to perhaps a hundred or so -- and that's under a dark, moonless sky.
If you want to give it a try, though, find a safe observing site away from city lights. The meteors enter the atmosphere from the direction of the constellation Perseus -- hence the shower's name. But they can streak across any part of the sky, so you don't have to look at a particular spot to see them.
Script by Damond Benningfield, Copyright 2011