Pretty Noisy

In this undated image made available from NASA shows the central region of a group of galaxies 300 million light-years away known as Stephan's Quintet. The distant galaxy is generating a 'sonic boom' of cosmic proportions, astronomers have discovered, as one of the galaxies falls towards the others at high speed, ploughing through a cloud of hydrogen gas travelling at 540.6 miles per second - 100 times faster than the speed of sound. The effect of this is similar to the sonic boom created by a fast jet. (AP Photo / Nasa via Pa)