Black Holes

You star was large enough, having more than four times the mass of the sun, it has 
become a black hole. Because of its immense gravity, it has become extremeely 
compressed. In fact it is so small, that not even light can escape. Black holes are not 
visible by the human eye, in fact they are even fainter than neutron stars, but we can 
detect it by the matter that swirls around the black hole before it enters.