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What is a Quasar?

Astronomical mysteries abound. Whenever something new is discovered, it presents an opportunity to peek into the unknown and learn even more about
the universe. Studying objects and phenomena that are happening millions of light years away is always challenging, but scientists persevere. Out in the cosmos, there are millions upon billions of stars, galaxies, nebulae, and all manner of strange and beautiful things. One such strange object was dubbed a quasar, and it took many different theories for us to figure out what they could be.

1. Quasi-stellar radio source.
The first given name for a quasar was “quasi-stellar radio source”. We now know that quasars don’t emit a lot of radio waves, but why choose a different name at this point? They were discovered when radio telescopes were first being used and presented a puzzle that astronomers are still trying to figure out.

2. You’ve heard of black holes.
Quasars and black holes go hand in hand. Supermassive black holes lie at the center of galaxies, and while some, like ours, no longer actively “feed” on material, there are many out there that do. We call these active feeders. These active feeders have an accretion disk swirling around them, and twin jets of material shooting out from either side. It’s these jets that identify quasars due to their incredible brightness. So, quasars are more or less powered by black holes.

3. They’re the brightest objects in the universe.
...that we know of. They’re also some of the farthest stellar objects we’ve been able to see. All the quasars we know of are incredibly far away from Earth, so it’s impossible to see them without help from telescopes. Still, their brightness allows us to study them at least partially, and refine current theories as not all are on board with the supermassive black hole idea. If not that, though, then what are they?
Jun 1, 2020

And because quasars are both so far and so bright they serve wonderfully as fixed reference points for things like, for instance, determining just how many milliseconds the Earth was either too slow or too fast to complete one day.