This image shows the infrared emission from the young star Fomalhaut and the dust disc surrounding it, as recorded with ESA's Herschel Space Observatory at a wavelength of 70 micron. To explain the emission from Fomalhaut's debris disc, astronomers invoke a steady production of dust particles via comet collisions, with an average rate of 2000 daily collisions between comets of one kilometre across or, alternatively, of 2 daily collisions between 10-kilometre-diameter comets.