ESA’s Herschel infrared observatory will have an unprecedented view of the cold universe, bridging the gap between what can be observed from ground and earlier space missions of this kind. Infrared radiation can penetrate the gas and dust clouds that hide objects from optical telescopes, looking deep into star-forming regions, galactic centres and planetary systems. Also cooler objects, such as tiny stars and molecular clouds, and even galaxies enshrouded in dust, which are barely emitting optical light, can be visible in the infrared.