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- 2012-7-19
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- 1970-1-1
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276 - 陨石和星云
P1 - Next week, a spacecraft NEAR should set off to study an asteroid.
P2 - When it reaches the destination, NEAR will spiral round the asteroid Eros and reveal what it is made of.
P3 - Researchers are hoping NEAR's study for Eros will help resolve the conundrum whether meteorites are spawned from asteroids.
P4 - Most asteroids live in the asteroid belt.
P5 - Parents of meteorites have to escape from the asteroid belt and head close enough to the Sun to cross the Earth's orbit.
P6 - The supply of asteroids must be continually replenished. So they probably come from the maini asteroid belt.
P7 - How do they escape from the asteroid belt? => Bodies within the asteroid belt sometime crash into each other and scatter fragments into chaotic orbits.
P8 - The small fragments of comets are weak and burn up easily in Earth's atmosphere. But asteroid fragments are made of stony material and may survive the fiery plunge and become the meterorites.
P9 - The chondritic meteorites presumably are just like the solid materials from which the Earth and other terrestrial planets formed.
P10 - The Earth, the Moon and the other planets have all evolved dramatically during their lives.
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