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Rhodes Unit 2
The Universe
Question | Answer |
---|---|
solar system | the collection of large and small bodies that orbit our central star, the sun |
planet | a spherical body that orbits the sun |
moon | a small body that orbits a planet |
star | a large celestial body that is composed of gas and emits light |
galaxy | a large collection of stars, gas, and dust that is held together by gravity |
light-year | the distance light travels through space in one year; about 9.46 trillion km |
universe | space and all the matter and energy in it |
clusters | areas where galaxies are grouped together; contain as many as several thousand galaxies |
superclusters | areas of ten or more clusters of galaxies |
voids | huge spherical areas where very little matter exists |
multiple star system | three or more stars that are bound together by gravity |
apparent magnitude | the measure of a star's brightness as seen from Earth |
luminosity | the actual brightness of a star |
absolute magnitude | a measure of how bright a star would be if the star were located at a standard distance |
white dwarfs | very small stars about the same size as Earth |
giant stars | very large stars that typically have sizes between 10 and 100 times the radius of the sun |
supergiants | rare, extremely large stars that have sizes of up to 1,000 solar radii |