A simile is a figure of speech that directly compares two things through some connective, usually like, as, than, or a verb such as resembles.. A simile differs from a metaphor in that the latter compares two unlike things by saying that the one thing is the other thing.
A galaxy is an enormous collection of gas, dust and billions of stars held together by gravity. One galaxy can have hundreds of billions of stars and be as large as 200,000 light years across.
Astronomy a large system of stars held together by mutual gravitation and isolated from similar systems by vast regions of space. (usually cap.) See Milky Way. any large and brilliant or impressive assemblage of persons or things:a galaxy of opera stars.