# Black Hole Image

Togo | 11:06 Wed 10th Apr 2019 | Science
Sometime today NASA will be releasing images of Sagittarius A, the black hole at the centre of our Milky Way galaxy. (No Mars bar jokes please). Brilliant science to gather and correlate the info using radio telescopes across the World that were synced with an atomic clock. It has taken 2 years to put the image together and I for one can't wait to see it. The link below contains some useful explanations of why and how it was done, and rather good explanatory videos.

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According to Dr Mark Morris “There is a speed limit to the spin of a black hole. It’s sort of set by the faster a black hole spins, the smaller is its event horizon.” https://www.universetoday.com/109308/how-fast-do-black-holes-spin/
07:38 Fri 12th Apr 2019
Question Author
I was ahead of the game at 12.04 it would seem.

https://thumbsnap.com/i/l5Wz5ckb.jpg
Togo: // Would a singularity not produce a dome of influence on the matter around it rather than a 2d flat plane? //

I think in the end I answered this question already. You are right that a perfectly spherical, static black hole would attract matter in all directions, but...

// ... this Black hole is rotating, so what you are seeing is a disc [of material spinning around the black hole]. //

It's not difficult to introduce a rotation. All it takes is for material to fall to the centre with even the slightly hint of angular momentum, and then because that is conserved, as the black hole gets smaller and smaller it will spin faster and faster. Imagine, for example, rolling a coin on the table. Doesn't take much for it to end up moving in ever-decreasing circles. That makes a particular disc "preferred" for the material to gather around, rather than just falling in from all directions.

Hope that helps!
Haaaaa! ^^^^
Question Author
Yes Jim, I came to that conclusion after putting a bit more thought into it. But the analogy I came up with is how an ice skater goes into a spin and is able to gain speed by drawing his/her limbs gradually towards the axis which then converts the energy into increased spin rate. Must be incredible rotation rates at a black hole centre. Faster than the speed of light?
According to Dr Mark Morris “There is a speed limit to the spin of a black hole. It’s sort of set by the faster a black hole spins, the smaller is its event horizon.”
https://www.universetoday.com/109308/how-fast-do-black-holes-spin/
Question Author
Ahh max speed is set at 84% the speed of light. The cosmic speed limit. Amazing.
Question Author
Thanks to Zacs for the link as I wouldn't have known without it.
I have to say I have just read this thread and the links and i now realise how incredibly stupid I am and how beautiful science is.
It was a bit od a struggle getting my head round it at half seven (after a few glasses of wine the previous evening!).

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