What is a quasar?
A quasar is an extremely bright center of a distant galaxy, powered by a supermassive black hole swallowing gas. Quasars can outshine their entire galaxy by thousands of times.
As gas spirals toward a supermassive black hole, it forms a hot, swirling disk that heats to millions of degrees and glows intensely across the spectrum, from radio waves to X-rays. Some quasars also shoot powerful jets of particles into space at nearly the speed of light.
Quasars were discovered in the 1950s and 1960s as radio sources that looked like stars, so they were called quasi-stellar radio sources. In 1963, astronomer Maarten Schmidt showed that one, 3C 273, was extremely far away, meaning it had to be unimaginably powerful. Most quasars are billions of light-years away.
Windows to the early universe
Because their light has traveled so far, quasars show us the universe as it was billions of years ago. The most distant known quasars existed less than a billion years after the Big Bang, which puzzles scientists about how their black holes grew so large so quickly.
Did You Know?
The quasar 3C 273 is bright enough to be seen with a good amateur telescope, even though it is about 2.4 billion light-years away.