Quasar

Quasars (quasi-stellar radio sources) are the most luminous persistent objects in the Universe, powered by supermassive black holes consuming matter at extraordinary rates. These cosmic beacons can outshine entire galaxies containing hundreds of billions of stars, despite their energy originating from a region smaller than our solar system around the central black hole.</p><p>Discovered in 1963 by astronomer Maarten Schmidt, quasars initially puzzled scientists because they appeared star-like but exhibited enormous redshifts, indicating vast distances. The most distant known quasar, J0313-1806, lies 13.03 billion light-years away, showing us the Universe when it was only 670 million years old. At peak luminosity, quasars can emit energy equivalent to trillions of suns—the record-holder, TON 618, harbors a black hole 66 billion times our Sun's mass.</p><p>These cosmic lighthouses serve as invaluable tools for studying the early Universe, galaxy evolution, and intergalactic medium. Their brilliant light allows astronomers to probe cosmic structures along their sight lines, while their extreme physics helps test theories of general relativity and accretion processes. As the Universe aged and galaxy mergers became less common, the quasar era largely ended, making today's active examples precious windows into our cosmos's violent youth.