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Comment by ustamills | Hacker News Reader

Wow, if we're seeing it that far in the past I wonder if maybe it's large enough to have eaten the universe already and we just don't know it yet.

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Black holes don't "eat" surrounding objects. Their gravity is no different from the gravity of any other object of the same mass. This hole has a mass between 10 and 100 million solar masses; that's about the size of a dwarf galaxy. So its gravity would be no stronger than a similarly sized dwarf galaxy. We are in no danger of having the universe eaten by dwarf galaxies.

If the Sun were replaced by one solar mass black hole, we would freeze/starve to death but the Earth's orbit would be just as stable as it is now.

In fact Earth might survive (as an ice planet) much longer than it would around the Sun since the Sun is expected to become a red giant and possibly swallow the Earth when it dies.

If the Moon were replaced by a black hole of its same mass, we wouldn't even notice except that the night sky would become moonless and we wouldn't have eclipses any more. The tides would keep happening as usual.

It will evaporate relatively immediately. So no tides.

It will take longer than the age of the universe to evaporate. So tides. For a while.

Moonlight is actually a very important influence in many natural cycles, all of which would be disrupted.

And as a motivator for both our intellectual curiosity and our scientific curiosity, the lack of a detailed moon in our night sky would have retarded the development of human civilization.

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