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“galaxies”
A congregation, or large grouping, of millions or billions of stars: A galaxy is held together by gravity or gravitational attraction and also known as an "island universe".
A galaxy can also be described as a collection of dust, gas, and stars measuring thousands of parsecs across.
A "parsec" comes from PARallax + SECond which is a unit of distance between stars. One parsec is about 3 1/4 light years.
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Astronomy and related astronomical terms
(page 11)
(the science of the celestial bodies: the sun, the moon, and the planets; the stars and galaxies; and all of the other objects in the universe)