Would it be a feasible scenario?
I have read this question:
Where Lubos Motl says:
The extremal Kerr J=GM2/c∼RbhMc. Now, the Earth-mass black hole has radius 9 mm or so so we get about 1030 Js. The Earth's spin, actual angular momentum now, is indeed over 1040, ten orders of magnitude too much. This discrepancy is of course linked to Earth's too low density that makes the collapse de facto impossible.
So based on this, the moon needs a radius of 2 mm. So let's disregard that the moon's low density makes it practically impossible to collapse, but let's instead say that it already is a black hole, size 2 mm, and nothing else, changes, it is revolving around the Earth, same speed, trajectory.
Would this be possible? Can a planet have a black hole moon at all?
Would anything on Earth change?