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Loading contentEncyclopedia · Glossary
A region of spacetime from which not even light escapes.
A black hole is a region of spacetime where gravity is so strong that nothing, not even light, can escape once it crosses the boundary. That boundary is called the event horizon, and it marks the point of no return.
Stellar-mass black holes form when the cores of the most massive stars collapse at the end of their lives. Supermassive black holes, millions to billions of times the mass of the Sun, sit at the centers of most large galaxies, including the Milky Way.
We cannot see a black hole directly, but we detect it through its gravity and through radiation from hot matter swirling around it. Telescopes have now imaged the glowing gas surrounding the shadows of supermassive black holes.