ESO’s submillimetre eye on the sky

The 12-metre dish of the Atacama Pathfinder Experiment (APEX) cuts a lonely figure in this aerial image of the Chajnantor Plateau in northern Chile (right of the centre). The snow visible in the background alludes to the frigid temperatures found at an altitude of over 5000 metres above sea level. This telescope is located in the arid, dry Atacama Desert, which experiences an average rainfall of only 100 millimetres per year.

Since first light in 2004, APEX has contributed much to our understanding of the Universe at submillimetre wavelengths in the areas of star and planet formation, very distant galaxies in the early Universe, and the conditions present in molecular clouds. Among the many astronomical insights APEX has given us, it was the first telescope to detect hydrogen peroxide in space and the first to observe a circumstellar disc around a young massive star.

APEX was created from a modified prototype antenna for ALMA, the Atacama Large Millimeter/submillimeter Array, located only a short distance away. ALMA is the world’s largest ground-based astronomical project currently in operation, and also focuses on star and planet formation both in the local and early Universe.