Galaxy

Spiral Galaxy NGC 4414 9925

A system of about 100 billion stars. Our Sun is a member of the Milky Way Galaxy, which is sometimes just designated by capitalization: Galaxy. There are billions of galaxies in the observable universe. Exactly when and how galaxies formed in the Universe is a topic of current astronomical research.

See also: Galactic Corona, Galactic Disc, Galaxy Clusters, Lenticular Galaxy, Seyfert Galaxy, Star, Starburst Galaxy, Supercluster, Universe.

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NASA Photographic Library Photographs from NASA available for viewing and download.