Paul’s Perseid Post

August 11, 2012

The sky will be mostly clear for peaking at the Perseids tonight. Experts say the show should start between 11pm and midnight, continuing through dawn Sunday morning. If you’re lucky you might see one or two a minute. A crescent moon will rise around 1 a.m., but it won’t have much effect.

Face east if you have a clear view in that direction, and look about half way up the sky from the horizon. You won’t need binoculars or a telescope because the meteors move much too fast for those. The chances of seeing a fireball will be greatest near dawn, when Earth will be moving head on into the meteor stream.

Most meteor showers happen when Earth crosses the orbit of a comet; the Perseids come from Comet Swift Tuttle. The meteors are caused by particles released from the comet’s nucleus and left behind in space. As Earth plows through this stream of debris, ranging in size from sand grains to pebbles, each particle slams into our atmosphere at a speed of more than 50 kilometers per second and burns up almost instantly from friction with air molecules. The resulting heat momentarily creates a streak of glowing air that we see as a meteor. All of this happens about 50 miles above the ground, regardless of how close some meteors may appear.

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