Perseid Meteor Shower

Every year, the Earth passes through debris paths left by comets hurtling past the Sun. Tiny particles burn up in the Earth’s atmosphere. We see them as bright streaks across the night sky and name them “shooting stars,” intense streaks of light across the night sky, caused by small bits of interplanetary rock and debris called meteoroids. Traveling at thousands of miles an hour, meteoroids quickly ignite, searing in the atmosphere’s friction, 30 to 80 miles above the ground. Most are destroyed during entry; the rare few that survive and hit the ground are known as meteorites.

Perseids by Lars Lindberg Christensen 

Of these annual intersections, the Perseid Meteor Shower is the most well-known. This shower occurs when the Earth enters the debris path left by the comet Swift-Tuttle on its last trip past the Sun in December 1992. As comets orbit the Sun, they shed an icy, dusty debris stream along the comet's orbit. If Earth travels through this stream, we will see a meteor shower. Depending on where Earth and the stream meet, meteors appear to fall from a particular place in the sky, maybe within the neighborhood of a constellation, known as a Radiant.

Timing a meteor shower’s peak is not precise, but according to the International Meteor Organization, the 2013 Perseid peak is expected from August 12, 5:15 am to August 13, 4:45 pm PDT. It’s worthwhile to observe on either side of this time. Estimate peak rates for the Perseid are near 50 to 60 meteors per hour, for those under transparent rural skies. Those under dark but hazy skies should still be able to see 30 to 40 Perseids per hour. Those under urban skies will be lucky to exceed 10 to 15 per hour. The Moon will be a waxing crescent approaching first quarter on August 14, so will set early enough not to create problems for observers.

Watching a meteor shower is easy! Choose an observing location which gives a wide view of the sky with as few obstructions as possible. If you're viewing from the city, try to observe where artificial lights obstruct the least. Meteor watching is basically an unaided-eye event but binoculars are handy for watching trails (persistent trains) that may hang in the sky for one or more seconds after a meteor's passage.

For early evening viewing, be outside about the time the first stars appear. The Radiant will be low in the northeast but don't concentrate just on that one area, but let your gaze wander over a large portion of the sky. Meteors that appear near the Radiant will have short paths while those that begin farther out have much longer ones. As the hours pass the Radiant rises higher and between about midnight and dawn the greatest number of meteors can be seen. Viewing through city lights will reduce their numbers considerably but the brighter ones will still show up nicely.




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