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Astronomers Discover Dark Galaxy Dominated by Dark Matter

2/19/2026

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Summary

Story summary

Astronomers identified Candidate Dark Galaxy-2 (CDG-2) with the Hubble Space Telescope.
CDG-2 lies about 300 million light-years away in the Perseus galaxy cluster.
CDG-2 is dominated by dark matter, with 99% of its mass in that form.
CDG-2 contains only a sparse population of stars, roughly equal to 1 million Sun-like stars, as reported in The Astrophysical Journal Letters.

History

Historical Context

In 1933, Swiss astronomer Fritz Zwicky first proposed dark matter while studying the Coma galaxy cluster, calculating that unseen mass accounted for about 90% of its total mass. His findings laid the groundwork for ongoing research into dark matter, which now constitutes approximately 85% of the universe's total mass, significantly influencing our understanding of cosmic structure and evolution.

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Story summary

Astronomers identified Candidate Dark Galaxy-2 (CDG-2) with the Hubble Space Telescope.
CDG-2 lies about 300 million light-years away in the Perseus galaxy cluster.
CDG-2 is dominated by dark matter, with 99% of its mass in that form.
CDG-2 contains only a sparse population of stars, roughly equal to 1 million Sun-like stars, as reported in The Astrophysical Journal Letters.

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