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Chapter 21
Stars, Galaxies and the Universe
Term | Definition |
---|---|
apparent brightness | the brightness of a star as seen from Earth |
absolute brightness | the brightness the star would have if it were a standard distance from Earth (must be calculated) |
light-year | the distance that light travels in one year (9.5 million, million kilometers) |
parallax | the apparent change in position of an object when you look at it from different locations |
nebula | a large cloud of gas and dust that is spread out |
protostar | a contracting cloud of gas and dust; beginnings of a star |
supernova | the explosion of a super giant star |
black hole | an object in space with enough gravity so strong that nothing, not even light can escape |
Milky Way | the spiral galaxy that includes our solar system |
constellation | an imaginary pattern of stars |
Hertzsprung-Russell diagram (H-R diagram) | used to classify stars and how they change over time |