The Perseids are building up to their zenith and I'm rather exciting. Apart from the Leonids later in the year these are the best meteors to view as an amateur. Usually bright with a good trail and usually lots of them. No waiting around for half an hour to catch the odd glimpse of a streak that if you blink you may miss it!
Checking the weather in my locality it looks as though I'm going to miss the build up this year. www.metcheck.co.uk has a good astronomy weather page and the predictions for the next few days look rather bleak. 100% cloud cover for today, 74% for tomorrow and 85% for Friday. Not particularly conducive for meteor shower observing. It looks as though I won't be submitting any details to the BAA or IMO this year.
So to the history of the Perseids. Located in the constellation perseus, the meteor shower have a mean zenith hourly rate (ZHR) of approximately 100. They are visible from July 17th until August 24th in 2008. Historically the velocity of the shower has been estimated at 59 km/s. The radiant for the shower is given as alpha = 046 degrees; delta = +58 degrees.
Commonly associated with the tail of comet Swift-Tuttle they occur due to the Earth's orbit slicing a path through the tail of the comet and hence encountering debris from the tail. Most of the meteors that you see from the Perseids are sand sized grains entering the upper atmosphere and igniting from atmospheric friction and never reach the earth's surface. Good thing really.
If you live in a Northern Hemisphere, good luck on your observations!
