Sources for the gravitational waves reaching us here on Earth are all cosmic events in which masses are accelerated. One example are supernovae: When stars with more than ten solar masses have exhausted their nuclear fuel, a gigantic explosion ensues called a supernova. Depending on the details of the explosion, the associated movement of matter can lead to a distinct gravitational wave pulse. The image shows the Crab nebula, remnant of a supernova explosion that was observed by chinese astronomers in the year 1054.