The Perseids have been upon us now for a few weeks, and are due to peek this weekend, the nights of the 10th through 12th. The shower itself actually runs for a few weeks, starting usually the second week in July and then running through the third week in August. The peak is always near the second week of August.
Like most meteor showers, the Perseids are associated with another larger body, in this case Comet Swift-Tuttle. This comet last paid a visit to the inner Solar System in late 1992, and has since been heading back into the depths of space.
|Chart courtesy The International Astronomical Union Minor Planet Center|
With an orbit that takes it out to a distance further than Uranus, Swift-Tuttle takes a leisurely 133 years to make a complete loop around. Its orbit, however, is steep compared to most of the planets.
The Perseids are the debris that Comet Swift-Tuttle left behind. This material spreads out along the comet's path, and starting in mid-July, the Earth begins encountering it. For the following few weeks, our planet passes through that path, and in doing so we get the Perseids.
In order to catch these little pieces of cometary debris, you need to stay up a little late, at least until after midnight local time. Look towards the northeast; after midnight, the constellation Perseus will begin rising over the horizon, and it is here that the meteor shower's "radiant" is found. If you follow the path of all the Perseid meteors, they should point roughly back towards this, even though they could be anywhere in the sky. This is also roughly the direction the Earth is moving. In a sense, the Perseids are akin to bugs on our planetary windshield.
|Chart created with Home Planet|
So, if you get a chance, try to stay up late and catch these little remnants of a comet that won't be in our part of the Solar System for another one hundred and thirteen years.