lecture19 - Astronomy Picture of the Day A map of the sky...

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Astronomy Picture of the Day A map of the sky in gamma rays, from the Fermi telescope
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Meteoroids, meteors, and meteorites Meteoroids : small chunks of rocky or metallic space debris (much smaller than an asteroid) Meteors : “shooting stars” The bright vapor trail left by a meteoroid while falling through the earth’s atmosphere Meteorites : the remaining fragments of meteoroids that land on earth
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Meteorites From radioactive dating, most meteorites are around 4.5 billion years old, and are fragments of disrupted asteroids Different types: Stony meteorites: rock and mineral composition Carbonaceous meteorites: contain rock and organic material- including amino acids Iron meteorites: mostly metallic, iron/nickel Some meterorites are known to have come from Mars or the Moon
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Types of stony meteorites Ordinary Chondrite: an agglomeration of dust and mineral grains including chondrules (formerly molten droplets of minerals that merged together to form asteroids) Achondrite: a stony meteorite that was once part of a larger body that experienced melting and differentiation Carbonaceous Chondrite: a chondrite with a high carbon content, including complex organic molecules
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Iron meteorites Origin: the cores of asteroids that were large enough to undergo differentiation Only a few percent of meteorites are iron meteorites But they are easy to recognize on the ground
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Meteorites Meteorites have been known to hit houses, cars, etc. .. But no deaths have ever been reported from meteorite falls
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Meteorites The largest meteorites known weigh tens of tons
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Comet debris and meteor showers After most of the ice in a comet has evaporated away after many orbits around the sun, the remaining bits of rocky material are not held together tightly They spread out and form a debris trail along the comet’s orbit
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Meteor showers As the earth plows through a trail of comet debris, meteors appear to come from a particular point in the sky called the radiant Meteor showers are named for the constellation containing the radiant: the Leonids, the Perseids, etc.
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Very thick debris trails lead to metor storms! 1833 Leonid shower: thousands
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This note was uploaded on 11/23/2010 for the course PHYSICS PHYSICS 20 taught by Professor Aaronbarth during the Winter '10 term at UC Irvine.

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lecture19 - Astronomy Picture of the Day A map of the sky...

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