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Last sync:2023-01-09 22:15
Hank explains how quasars and blazars are both the same thing - just oriented differently in respect to us - and how that impacts the way we perceive them and how it also effects the ways we can study them.

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On the planet that I'm from, this is known as toilet paper. That's toy-let pay-pur. But I'm not here to discuss personal hygiene today. This is about astronomy and how we name things.

As shapes go, this toilet paper is a cylinder, but if you look at it directly like this, then it's a circle. I know, your minds are totally blown and you're probably wondering when we are start talking about astrophysics but imagine for a second that we call things by different names depending on the angle we saw them from. If I were holding it like this, we'd call it a roll of toilet paper but if I showed it to you this way we'd call it a sanitation ring or a hoop of cleanliness or something.

That wouldn't make a lot of sense since we get to study toilet paper rolls from whatever angle we want to when we want to which was probably not very often.

But in astronomy we don't get to do that. We have to study the objects that we see in whatever angle they happen to be relative to our planet. At least so far we can't pick them up and spin them around yet.

So sometimes in astronomy we call the same object a different thing depending on what angle we are viewing it at, and that's the case with quasars and blazars, and it makes a lot of sense. Because, while quasars and blazars are technically the same thing they look very different from our perspective and they allow us to understand the universe in very different ways, which is pretty cool.

Quasars and blazars are types of active galaxy nuclei which meaning that their galaxy is big enough and has enough energy and the black hole at the center is massive enough that it forms an accretion disk around it and then from it's center it accelerates a massive amount of stuff in a single jet in a 90° angle from the plane of the galaxy. These active galaxy nuclei are the brightest persistent objects in the universe and that's even more true when you look at them straight on.

Quasars are a type of active galaxy nuclei viewed at an angle and they are lots of them and we've studied them for decades. Blazars, on the other hand, are the same type of galaxy nuclei but they are much more rare because they are when we are looking at the galaxy nucleus straight on it's head light a flashlight shining straight into our eyes.

This leads to all sorts of weirdness because the particles accelerated out of the black hole are often moving at close to the speed of light, while they're also emitting energy at the speed of light. When studying blazars we get to study in practice, while throwing a baseball from a train moving at the speed of light would not violate Einstein's relativity. 

Blazars create all kinds of weird effects like Doppler boosting which makes them look ever brighter then they are, sometimes brighter than all of the stars in the galaxy they originate from combined. So, just because of the angle that they're facing us at, they appear to be completely different to us and act in different ways than quasars.

Now with all of the fun stuff in science, the difference between quasars and blazars remains controversial but many astronomers have concluded that they are, in fact, the same thing, just seen at different angles. Quasars are what we see at a glancing angle while blazars are just quasars that we see looking straight down the jet.

Hopefully I helped clean up some of that confusion.

Thank you for watching this episode of SciShow. If you have any questions or comments or ideas for us, please leave them on Facebook or Twitter or in the comments below. And if you want to keep getting smarter with us you can go to and subscribe. 

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