A mirror to the past

The sunset seen in this Picture of the Week creates a magnificent setting over the telescope village of ESO’s La Silla Observatory in the Chilean desert. La Silla is home to many telescopes, some still in active use, like the ESO 3.6-metre telescope situated at the highest summit to the right and currently on the hunt for exoplanets. 

Some of La Silla’s telescopes have been retired, like the Swedish-ESO submillimetre Telescope (SEST) that’s seen in the foreground with its shiny 15-metre dish. Built in 1987, SEST was at the time the largest telescope of its kind in the southern hemisphere. Thanks to its wavelength range, it enabled scientists to study the very distant Universe, and to make many exciting discoveries related to stellar nurseries. 

As time passed, new technology brought forth more advanced telescopes, which also observe in the (sub)millimeter part of the spectrum, such as the Atacama Pathfinder Experiment (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA) which ESO partners with. Close to APEX and ALMA seeing first light, SEST was decommissioned in 2003. Still standing at La Silla, SEST acts like a mirror, allowing us not only to see the reflection of the desert and the sky, but also provides a mirror to the past of astronomical exploration.