The Perseids are bits of debris from Comet Swift-Tuttle, which has laid down several streams of debris, each in a slightly different location, over the centuries as it orbits the sun. Every August, Earth passes through these debris streams, which spread out over time.


"They are typically fast, bright and occasionally leave persistent trains," says Joe Rao, SPACE.com's Skywatching Columnist. "And every once in a while, a Perseid fireball will blaze forth, bright enough to be quite spectacular and more than capable to attract attention even in bright moonlight."


Low numbers of Perseids, including some bright fireballs, have already been reported as Earth began entering the stream in late July. Seasoned observers have counted up to 25 per hour already, or nearly one every two minutes.


Most meteors are no bigger than a pea. They vaporize as they enter Earth's atmosphere, creating bright streaks across the sky.


The Perseids appear to emanate from the constellation Pers

Will this also be visible in the southern hemisphere?

The best time to watch is between midnight and dawn Wednesday. Forecasters say the best stretch could come between 4 a.m. and 5 a.m. ET (1-2 a.m. PT), which would be after daybreak in Europe. Some Perseids might be visible late Tuesday night, and Wednesday night into Thursday morning could prove worthwhile, too.

Twitter! It has a lot of uses, including those astronomical and meteorical: the Newbury Astronomy Society has started Twitter Meteorwatch, where you can follow the Perseids online, get links to live webcams, and ask questions about the shower as well. Just use the hashtag #Meteorwatch when tweeting.

http://blogs.discovermagazine.com/badastronomy/2009/08/10/tweeteor-shower/