An extremely luminous active galactic nucleus powered by a supermassive black hole. Quasars can outshine entire galaxies and are among the most distant observable objects. Short for quasi-stellar radio source.
A region of spacetime where gravity is so strong that nothing, not even light, can escape once past the event horizon. B...
A rotating disk of gas, dust, and other matter that forms around a massive body such as a black hole, neutron star, or y...
A gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range from ...
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