Chocolate hills in the middle of the desert

A vista of smooth, chocolatey hills fills this Picture of the Week. The emptiness of this aerial photo is broken only by a white round building at its centre: the ESO 3.6-metre telescope at La Silla Observatory in the Chilean Atacama desert.

Located at an altitude of around 2400 metres above sea level, the telescope started observing the sky in November 1977. This remote area has one of the darkest night skies on the Earth, allowing the telescope to observe the wonders of the night sky undisturbed. In particular, the ESO 3.6-m telescope hosts one of the most successful planet finder instruments: the High Accuracy Radial velocity Planet Searcher (HARPS), which measures the subtle gravitational tug that planets exert on their host stars as they orbit around them.