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Chapter 21

Vocab

QuestionAnswer
asteroids Millions of small,rock objects
comet A object made of gas,dust and ice that move around the sun
Astronomical unit The average distance from earth to the sun
period of revolution The time it takes to an object to travel one around the sun
period of rotation The time it takes an object to complete one rotation
Terrestrial planets The planets closest to the the sun
Greenhouse effect When a planet's atmosphere traps solar energy and causes the plant's temperature to increase
Galilean moon The largest moons of Jupiter
meteoroid A small rocky particle that moves through
Meteor A meteoroid that entered Earth's atmosphere
Meteorite A meteor that hit a plant or moon
Impact crater The impact of a meteor
Created by: campbisa1
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