Why are quasars so bright?
Show answer & explanation
Answer: Matter falling into black holes
Exploding galaxies releasing energy — Wrong. Quasars aren't explosions—they're powered by continuous accretion of matter onto supermassive black holes, releasing enormous energy.
Matter falling into black holes ✓ — Correct! Quasars (quasi-stellar objects) are extremely luminous active galactic nuclei powered by supermassive black holes (~millions to billions of solar masses). Matter spiraling into black holes forms accretion disk, heated to millions of degrees by friction and gravity. This emits intense radiation—some quasars outshine entire galaxies! Most distant quasars are billions of light-years away (early universe). As matter supply decreases, quasars fade!
Clusters of billions of stars — Wrong. Quasars are in galaxy centers, but brightness comes from black hole accretion, not just star clusters—far brighter than stars alone.
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