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Ask an Astrophysicist

The Question

(Submitted December 05, 2000)

What is the average size of a galaxy?

The Answer

Thank you for your question. Our Milky Way galaxy is a pretty typical large galaxy. Most of the stars are in a disk that is about 100,000 light years across in diameter and 3000 light years thick. Most of the galaxies in the universe are actually smaller than the Milky Way. For example, most of the dozens of galaxies in our Local Group are at least ten times smaller in diameter.

-- Michael Loewenstein and David Marsden for "Ask an Astrophysicist"

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