Will the Sun form a black hole that sucks up all the planets? Do we know of any other black hole that will "eat" the Earth?
A). No and no.
1). First of all, according to the best current theory, the sun's mass isn't enough to collapse into a black hole when it's finished being a normal star. But more interesting ... even if it did, that would just mean that its mass would be concentrated in a much smaller volume. Seems to me that the effects of gravitation at 93 million miles from its center ... right where we are now ... wouldn't change. The earth, or what's left of it by that time, and the other planets, or what's left of them, would continue to orbit that central mass, just as we all do now, but in cold darkness.
2). Same idea for other bodies preparing to eat the earth. Black holes don't suddenly become colossal vacuums that go around inhaling everything. A 'hole' is still a mass equivalent to a large star. There's some distance, like a few miles or a few hundred miles or a few thousand miles, within which the escape velocity exceeds the speed of light, so from within which nothing can escape. But at greater distances, the effects are no different from what they were when the hole was still a star.
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