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15 Cards in this Set
- Front
- Back
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Comet |
Loose collections of ice, dust, and small rocky particles whose orbits are usually very long, narrow ellipses |
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Coma |
Clouds of gas and dust form a fuzzy outer layer around a comet |
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Nucleus |
The solid inner core of a comet |
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Kuiper belt |
A doughnut shapes region that extends from beyond Neptunes orbit about 100 times Earths distance from the Sun |
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Oort cloud |
A spherical region of comets that surrounds the solar system from about 1000 to 10000 times the distance between Pluto and the Sun |
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Asteroid |
Rocky objects that revolve around the Sun in fairly circular orbits between the orbits of Mars and Jupiter |
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Asteroid belt |
The region in the solar system where most asteroids revolve around the Sun between Mars and Jupiter |
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Meteoroid |
A chunk of rock of dust in space |
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Meteor |
A chunk of rock that enters Earths atmosphere and gradually burns up |
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Meteorites |
Meteors that pass through the atmosphere and strike Earths surface |
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Light year |
The distance that light travels in one year, 9.5 million million kilometers |
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Heliocentric |
A model system in which Earth and the other planets revolve around the Sun |
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Geocentric |
A model of the universe in which Earth is at the center of the revolving planets and stars |
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Nuclear fusion |
The process by which hydrogen atoms join together in the sun's core to form helium |
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Astronomical unit |
A unit of measure equal to Earth's average distance from the sun, about 150 million kilometers |
