Black holes are becoming stranger ― even to scientists who study planets and other objects in outer space.Astronomers recently reported the discovery of the signal from a violent collision of two black holes.The event, which took place long ago, created a new black hole of a size that scientists had never seen before.California Institute of Technology physicist Alan Weinstein was part of the discovery team.He noted that the finding was the “biggest bang” ever observed by human beings since the Big Bang.The Big Bang is a term many astronomers use to explain the beginning of the universe.Black holes are compact areas of space. They are so dense that not even light can escape. Until recently, astronomers had observed them in two general sizes.There are “small” ones called stellar black holes. These black holes are formed when a star collapses. They are about the size of a small city.There are also supermassive black holes. These black holes are millions, maybe billions, of times more massive than our sun.