High Accuracy Radial Velocity Planet Searcher
Udry's initial research concerned the dynamics of galaxies. His current work chiefly concerns the search for extra-solar planets by analyzing variations in the radial velocities of stars. Among them was Gliese 581c (announced April 25, 2007) which at the time, was the most likely candidate for habitability of any extrasolar planet discovered so far. The planet was discovered by analyzing data obtained by the High Accuracy Radial Velocity Planet Searcher (HARPS) on the European Southern Observatory's 3.6 meter telescope at La Silla Observatory in Chile.