Glossary term: Galactic Halo

Description: The galactic halo is a roughly spherical distribution of stars, gas, and dark matter which extends above, below, and beyond the disk of the Milky Way. Stars in the halo are older and have a lower metal content than most of the stars in the disk of the Milky Way. In the region around the Sun only a few percent of the stars are from the halo. Globular clusters of stars are also found in the galactic halo.

An invisible halo of dark matter also extends through and around the Milky Way, containing most of the Galaxy's mass.

Most other galaxies also have haloes.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

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