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The Universe
Term | Definition |
---|---|
solar system | the sun and all of the planets and other bodies that travel around it |
planet | a celestial body moving in an elliptical orbit around 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 light travels in one year |
universe | Space and all the matter and energy in it |
H-R diagram | Hertzsprung-Russell diagram, a graph that shows the relationship between a star's surface temperature and absolute magnitude |
apparent brightness | apparent magnitude is a measure of how bright a star appears from Earth/observer |
luminosity (absolute brightness or magnitude) | the actual brightness of an object/star |
astronomical unit (AU) | the average distance between Earth and the sun, approximately 150 million km |