Perseid Meteor Shower
Written by John Carl Villanueva
The Perseid Meteor Shower is caused by debris coming from the Comet Swift-Tuttle (not to be confused with Comet Tempel-Tuttle which causes the equally spectacular Leonid Meteor Shower).
One of the main components of comets is ice. So when a comet passes near the Sun, a part of it vaporizes and is ejected from the main body. The ejected components form a stream of particles that follow the outline of the comet's orbit. When the Earth intersects with this path (or in other cases, come close to it), the particles then enter the Earth's atmosphere.
Once in the atmosphere, gravity pulls them downward into a high-speed plunge. Because they are mostly very small, virtually all of them readily ignite and disintegrate. We then observe them as streaks of light as they burn up. They can number by the hundreds to hundreds of thousands per hour, hence the name meteor shower.
The Perseid meteor shower is always seen from Earth as if coming from the constellation Perseus. It is for this reason that the Perseid meteor shower, and all other meteor showers for that matter, is named as such. The apparent source of the shower is more commonly known in astronomy circles as the radiant.
Observed since 2,000 years ago, the Perseid meteor shower is also known to some Catholics as the 'tears of Saint Lawrence' because the time when it peaks (early August) usually coincides with the saint's martyrdom. The event actually begins in mid-July but usually peaks at around August 10-12. This is the time when our planet is bathed inside the densest portion of the debris stream.
In the non-peak times, you may catch less than 10 meteors per hour. But during the peak times, 60+ of them can be visible in just one hour.
The meteor shower is most visible in the Northern hemisphere. However, for as long as you have a clear sky and standing in a dark area, you can easily spot the streaks of light wherever you are on Earth. If you're lucky, you can even catch a fireball. A bright moon can also prevent you from viewing the shower in all its magnificent glory.
Sometimes, a brilliant streak of light caused by an Iridium flare can be mistaken for a fireball. Newbie astronomers can easily be fooled because the Perseid meteor shower can cover a big part of the sky. The Iridium flares actually come from any of the 66 satellites that make up the Iridium Satellite Constellation.
Allow us to share previous announcements here at Universe Today regarding the Perseid Meteor Shower:
2009 Perseid Meteor Shower – Double Peaks This Year!
Perseid Radio Astronomy from the Fourth Plinth With Chris Lintott
From NASA, there's a very recently published article entitled: The Perseids are coming. Another informative article, published in 2007 and titled: Great Perseids, can also be found there.
Astronomy Cast has the following related episodes:
Meteor Showers. Yes, the sky is falling.
Getting Started in Amateur Astronomy
Filed under: Astronomy
Related stories on Universe Today
- 2007 Perseid Meteor Shower Didn't Disappoint
- Another Reminder, Go See the Perseids
- The 2005 Perseid Meteor Shower
- Meteors Hitting Earth
- 2008 Perseid Meteor Shower Peaks On August 12 – But Start Now!
