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ScienceSpace

Perseid Meteor Shower August 11th – 12th 2012

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On August 11th-12th, 2012, the Perseid meteor shower will peak in intensity, several meteors will be visible streaking across the sky every minute.

The exact peak will be around 2am early Sunday morning (Saturday night), on August 12th. The moon will be in its waning crescent phase during this time so the sky will be fairly dark and good for viewing.

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“Every August, the night sky is peppered with little bits of comet debris in what we call the annual Perseid meteor shower. The Perseids are bits of the comet Swift-Tuttle and often create the most amazing meteor shower of the year.”

“Perseid meteoroids (which is what they’re called while in space) are fast. They enter Earth’s atmosphere (and are then called meteors) at roughly 133,200 mph (60 kilometers per second) relative to the planet. Most are the size of sand grains; a few are as big as peas or marbles. Almost none hit the ground, but if one does, it’s called a meteorite.”

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The Perseids are created from the “Comet Swift-Tuttle, which is the largest object known to make repeated passes near Earth. Its nucleus is about 6 miles (9.7 kilometers) across, roughly equal to the object that wiped out the dinosaurs.”

“Back in the early 1990s, astronomer Brian Marsden calculated that Swift-Tuttle might actually hit Earth on a future pass. More observations quickly eliminated all possibility of a collision. Marsden found, however, that the comet and Earth might experience a cosmic near miss (about a million miles) in 3044.”

“When a Perseid particle enters the atmosphere, it compresses the air in front of it, which heats up. The meteor, in turn, can be heated to more than 3,000 degrees Fahrenheit (1,650 Celsius). The intense heat vaporizes most meteors, creating what we call shooting stars. Most become visible at around 60 miles up (97 kilometers). Some large meteors splatter, causing a brighter flash called a fireball, and sometimes an explosion that can often be heard from the ground.”

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“Comet Swift-Tuttle has many comet kin. Most originate in the distant Oort cloud, which extends nearly halfway to the next star. The vast majority never visit the inner solar system. But a few, like Swift-Tuttle, have been gravitationally booted onto new trajectories, possibly by the gravity of a passing star long ago.”

“Swift-Tuttle’s orbit has been traced back nearly 2,000 years and is now thought to be the same comet that was observed in 188 AD and possibly even as early as 69 BC.”

Source: Space and Wikipedia

Image Credits: NASA/MSFC/D. Moser, NASA’s Meteoroid Environment Office; NASA/JPL; Perseid and Sky via Wikimedia Commons




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