The annual Perseid Meteor shower is in full bloom tonight (11 August 2009) for those living in the Northern hemisphere.
The Perseid meteor shower has been observed for over 2000 years, first being recorded in China. In early medieval Europe, the Perseids came to be known as the "tears of St. Lawrence."
The Perseid Meteor shower actually starts each year in July as the earth begins to move through the meteor stream, with tonight (August 11) and Wednesday morning (August 12) being the peak of activity in the sky.
The best time to view the meteor shower if you're in the United States is Wednesday morning at 1:00 a.m. EST and at 5:30 a.m. EST. At the peak, you'll see between 50 to 150 meteors an hour in the night sky, although you will see meteors at other times during the night. Best viewing is away from city lights, and obviously cloud cover.
If you're in the Southern hemisphere, parts of the meteor shower may be viewable depending on where you're located, although many in the far south will miss out as most of the activity is over the horizon.