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The first ever image of a black hole shows a circular black central portion surrounded by an illuminated accretion disk.

enter image description here

If a black hole wraps spacetime completely around it, then in any direction it should look like a fireball totally illuminated in all directions.

Why does the actual image show black in the centre, or again it is only imagination by slicing the sphere?

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  • $\begingroup$ While it’s true that black holes can bend light so severely as to make the entire area directly outside of the event horizon visible at any angle, this bent light does not somehow override the path lengths absent of light that come from within the event horizon; all the path lengths and their corresponding light or lack thereof are present before us, making the image that we see. Forgive the improper use of the term path lengths here, I just can’t think of a closer phrase that captures the idea here. $\endgroup$
    – Justin T
    Oct 15, 2021 at 16:07
  • $\begingroup$ Technically, the shadow is NOT circular - the noncircularity of the ring is a prediction of General Relativity. You said, "If a black hole wraps spacetime completely around it, then in any direction it should look like a fireball totally illuminated in all directions." Do you mean "warps" instead of "wraps?" Outside of the event horizon, spacetime is completely regular. $\endgroup$
    – Daddy Kropotkin
    Oct 15, 2021 at 17:44
  • $\begingroup$ That ring isn't the accretion disk. The latter isn't visible in the pic. Yes indeed "is a globe". The key is that you see or detect what reaches your eyes or antennas. $\endgroup$
    – Alchimista
    Oct 16, 2021 at 15:25

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This black hole is not spherically symmetric.

The black hole has angular momentum (it is spinning) and it is surrounded by a disc of matter that is orbiting it. This disc is in a particular plane, around the equator of the black hole.

The distortion of space time allows us to see the disc on the back of the black hole (if there was no distortion, that part of the disc would be hidden behind the black hole) But it situation is not fully symmetric and so there is no surprise that the image is not a "fireball totally illuminated in all directions". In fact when we model what a black hole "should" look like (accounting for the limits on the resolution) it should look exactly like this.

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