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the universe :)
unit 2
| Term | Definition |
|---|---|
| solar system | the sun and all of the planets and other bodies that travel around it |
| planet | a relatively large spherical body that orbits a star |
| star | a large celestial body that is composed of gas and that emits light; the sun is a typical star |
| galaxy | a collection of stars, dust, and gas bound together by gravity |
| light-year | the distance that light travels in one year; about 9.46 trillion years |
| universe | space and all the matter and energy in it |
| solstice | the point at which the sun is as far north or as far south of the equator as possible |
| star | a large celestial body that is composed of gas and that emits light; the sun is a typical star |
| apparent magnitude | the brightness of a star as seen from Earth |
| luminosity | the actual brightness of an object such as a star |
| absolute magnitude | a measure of how bright a star would be if it were seen from a standard distance |