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(Astronomy) the former name for galaxy
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|Noun||1.||extragalactic nebula - (astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust; "`extragalactic nebula' is a former name for `galaxy'"|
astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole
aggregation, collection, accumulation, assemblage - several things grouped together or considered as a whole
spiral galaxy, spiral nebula - a galaxy having a spiral structure; arms containing younger stars spiral out from old stars at the center
Great Attractor - a massive grouping of galaxies in the direction of Centaurus and Hydra whose gravitational attraction is believed to cause deviations in the paths of other galaxies
Milky Way, Milky Way Galaxy, Milky Way System - the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky
star - (astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior
cosmos, macrocosm, universe, world, existence, creation - everything that exists anywhere; "they study the evolution of the universe"; "the biggest tree in existence"
cosmic dust - clouds of particles or gases occurring throughout interstellar space