ESA Science & Technology - Fact Sheet

Unique to Europe was the very first space mission for measuring the positions, distances, motions, brightness and colours of stars - for astrometry, as the experts call it. ESA's Hipparcos satellite pinpointed more than 100 000 stars, 200 times more accurately than ever before. As astrometry has been the bedrock of the study of the Universe since ancient times, this leap forward has affected every branch of astronomy. The primary product from this pioneering and successful mission was a set of stellar catalogues, The Hipparcos and Tycho Catalogues, published by ESA in 1997.