Question: what is your favourite black hole or the biggest black hole you've seen?

Lucien Heurtier answered on 14 Mar 2023:

TON 618 is technically a big quasar that contains the most massive known black hole, with a mass of 66 billion solar masses. I have never seen it myself though 🙂

You may have heard in the news in the last few years that telescopes from all over the world have joined their efforts to take a picture of the black hole at the centre of our galaxy (you can google it!). That’s really nice because you can see what it looks like!

Black holes are a little weird because they look black at the middle, but they are so massive that things around them turn super fast, so they have a sort of luminous ring around them. But because black holes deform spacetime around them quite a lot, this ring looks more like a coat!