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Unit 2 Lesson 1
Universe Vocab
Term | Definition |
---|---|
astronomical unit | a unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun. |
revolution | the movement of an object in a circular or elliptical course around another or about an axis or center |
rotation | the action of rotating around an axis or center |
galaxy | a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction |
planet | a celestial body moving in an elliptical orbit around a star |
light year | a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 |
solar system | the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets |
star | a fixed luminous point in the night sky that is a large, remote incandescent body like the sun |
universe | all existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light years in diameter and contains a vast number of galaxies |