Today's useless fact - What exactly is a "black hole" and how does it suck up light?

A black hole is the result of a massive star that has collapsed. Every celestial object has what is known as an 'escape velocity'. The more massive and dense an object, the larger the escape velocity will be. The escape velocity of a celestial body is the speed required to get away from the celestial body into space and be able to leave completely, not just orbit it.

What a makes a black hole black, is that it has an escape velocity so great, that not even the speed of light can escape. When light approaches a black hole, it begins to bend, in accordance with Einstein's work which showed that the massive objects bend space-time.

When light crosses the boundary known as the 'event horizon', light is bent so far to the point where it is directed into the center of the black hole (through a type of orbit).

Now, if light cannot escape the gravitational pull of a black hole, then nothing else can since nothing can travel faster than the speed of light.

This is the reason a black hole is black. Evidence for black holes is present but there isn't any actual hardcore proof. The reason being is most information analyzed from space is acquired through Electromagnetic radiation (visible light, x-rays, ultraviolet light, radio waves, etc). But a blackhole absorbs all EM radiation, therefore we get nothing. What we have seen though, is a star or other massive objects orbiting something black/invisible. The only explanation could be a black hole. Also, astronomers caught a glimpse of gas being pulled from a star and traveling into something black. Check out the links in our Black Hole category for more.