In the center of our galaxy, there is a Supermassive black hole. We were told in early astronomy units of school that black holes are giant vacuums that will absorb/consume the area around it. My question is, how do remain in balance with the black hole so that it does not consume us, but that we actually orbit around it?
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The picture of a black hole being like a huge vacuum is pretty misleading, not to say wrong. The gravitational field around the black hole is exactly the same as around any other object of the same mass. Like any other object, it's perfectly possible to orbit a black hole, just like we orbit the Sun and don't fall in. In fact, if you were to magically replace the Sun with a black hole of the same mass, the Earth's orbit wouldn't change at all.
There are a couple of reasons the vacuum analogy is used. One is that black holes usually have accretion disks, big disks of glowing matter being sucked in. Again, this is no different than what would happen if you had a star instead of a black hole. The other, probably more important reason is that when you cross the event horizon of a black hole, it's impossible to get out. But that's about it. A planet orbiting a black hole (never mind one at the edge of the galaxy) would be in no real danger of being sucked in.
Javier
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You've the answer in your statement:
...black holes are giant vacuums that will absorb/consume the area around it.
The key is that the area around it is a few times the event horizon of the black hole and we are very far from the event horizon of the supermassive black hole at the center of the Milky Way. The event horizon for Sag A* (the name of the SMBH) is about 0.0041 light years and we sit around 25,000 light years away from it. Since we're so far away, the "giant vacuum" action simply doesn't exist--you may want to read this short article Is a black hole a giant cosmic vacuum cleaner? over at "Hubble Site."
Kyle Kanos
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