I get the explanation that they have gravity and things are attracted, but why is it in a ring rather than a sphere? why do things from one AXIS get attracted but not from other?
In: 49
Do you mean the ring of light/dark or the accretion disk?
The ring of light/dark happens because the hole itself absorbs light but around it light is lensed. This means that whatever is behind it, the light from that gets bent around the hole and you see it on all sides. This produces a ring, or usually several rings, around it. [Example image.](http://www.nasa.gov/sites/default/files/thumbnails/image/simulated_bh.jpg) Because it is an optical phenomenon, the rings appear to move as the observer does, so it always appears as a perfect ring.
As for the accretion disk, consider how orbits work. Matter always orbits in a flat plane. Around a bhole, there’s a bunch of matter. At first, it’s moving every which way. All of those orbits produce a sphere. However, all of those orbits must cross eachother to make a sphere, so they eventually collide.
All of these collisions serve to average out the velocity of the matter until it ‘agrees on’ a direction of spin. Once it is all spinning the same direction, it must all orbit on the same plane, and so you’re left with a disk.
Latest Answers