Twenty years ago, on the 24 April 1990, the Space Shuttle Discovery launched the Hubble Space Telescope, a joint NASA-ESA mission. Its discoveries have resulted in, quite probably, the most significant advances in astronomy since Galileo's telescope. It has provided the world's scientists with profound and unforeseen insights into the Universe, with hundreds of thousands of images of astounding beauty. The space telescope has greatly increased the publics curiosity and fascination for the mysteries of the Universe and our place in it.