Black Holes

Today, I was playing with my marbles. I made a funnel (by making it not steep) and rolled the marbles. They went in a spiral sort of shape and circled around, even around the hole at the bottom and then fell through the hole.( In malls you would drop the coins on it). Well, do you know that we have something like that in outer space. It is called as a black hole. A black hole is when gravity has a stronger force. You can make a black hole too by using these materials : marbles and a circular sloped surface. Push the marbles so that it revolves around and around until it stops. It will stop when it reaches center of gravity. Center of gravity is the point where something is stable. Because of gravity, we can walk on the ground. If there was no gravity,we wouldn't be able to walk or keep anything in place because everything would be floating around.