Quasars are?

• A. A kind of star.
• B. A planet with rings.
• C. An extremely luminous active galactic nucleus powered by gas spiraling into a massive black hole.
• D. A distant galaxy without any black holes.

Answer: (C)

Quasars are an extremely luminous active galactic nucleus powered by gas spiraling into a massive black hole at the center of a distant galaxy. The gas forms an accretion disk around the black hole, heating up as gravity converts potential energy into radiation. This process can outshine the entire host galaxy and emit across many wavelengths, sometimes with jets shooting out from the center.

So, quasars aren’t stars—they don’t shine from fusion in their cores. They aren’t planets with rings, which would be far too faint to produce the observed brightness. And they aren’t distant galaxies without black holes—the defining feature of a quasar is that active central engine powered by accreting material onto a supermassive black hole at the galaxy’s core.