English: In the search for distant worlds, few telescopes have had as much success as ESO's 3.6-metre telescope and the Swiss 1.2-metre Leonhard Euler Telescope, both of which are shown in this image.

The 3.6-metre telescope is home to HARPS (High Accuracy Radial velocity Planet Searcher), a spectrograph with unrivalled precision, and holder of many records in the field of exoplanet research, including the discovery of the least massive exoplanet, as well as of the smallest ever measured. Together with HARPS, the Leonhard Euler Telescope has allowed astronomers to find that six exoplanets from a larger sample of 27 were orbiting in the opposite direction to the rotation of their host star — providing an unexpected and serious challenge to current theories of planet formation.

At 2400 metres above sea level in the southern part of Chile’s Atacama Desert, La Silla was ESO’s first observation site. Along with the 3.6-metre telescope, it also hosts the New Technology Telescope (NTT) and the MPG/ESO 2.2-metre telescope as well as several national and smaller telescopes.