What’s an extremely powerful source of energy in the universe? It’s a quasar and it mystified astrophysicists and astronomers for a long time after they were discovered in the late 1950’s. Their discovery by radio telescopes was baffling because there were no visible objects that corresponded to their sources.

A quasar is now known to be an extremely powerful and very distant active galactic nucleus. Quasars were first identified as being high redshift sources of electromagnetic energy. They emit radio waves and visible light, that are point-like and similar to stars. This is rather unexpected and you would expect extended sources of energy and light since they are galaxies.

The original controversy over the nature of these powerful objects now in the past since now there is a scientific consensus that a quasar is a compact region 10-10,000 Schwarzschild radii. That’s the radius across the central super massive black hole at the center of a galaxy.