Forecast Calls for Shooting Stars
August 12, 2015
Professional and amateur astronomers will be in for a treat tonight. The Perseid meteor shower peaks in the evening hours and early tomorrow morning. If you look up, you may be lucky enough to see dozens of bright streaks flashing across the night sky.
Meteor showers occur when Earth travels through a stream of meteoroids. A meteoroid is a piece of matter that enters Earth’s atmosphere at a high speed. The rate at which meteors appear generally increases, peaks, and then decreases as Earth moves in and out of a stream. As seen from the ground, all the meteors in a particular shower appear to come from the same direction in the sky. This direction is called the radiant of the shower. The Perseids get their name because their radiant lies near the constellation of Perseus in the northern sky.
The Perseids are an annual meteor shower caused by a dusty trail of debris left by Comet Swift-Tuttle. As this comet orbits the sun, it sheds rock and dust particles. As Earth travels through this ring of debris, meteoroids crash into Earth’s atmosphere. Their high speed heats up the air, causing it to glow. These meteoroids are far too small to reach Earth’s surface and instead burn up in the atmosphere.
Comet Swift-Tuttle leaves a wide swath of debris, so meteors have been visible for several weeks already and will probably be visible for several more. The meteors are expected to peak tonight, however, as Earth passes through the thickest part of the debris cloud. The moon will be almost new tonight as well, so a dark sky will enable even more meteors to be seen. Look toward the constellation Perseus tonight after sunset to catch the show.
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