Llullaillaco

This image, taken in July 2012, shows Llullaillaco, a volcano in Chile's Atacama Desert. The visibility of the volcano from the observatory at Paranal depends on two circumstances: a fortunate geometry and the superb quality of the atmosphere over the Atacama Desert, stretching over a baseline of 190 kilometres, much longer than in any astronomical observation. To learn more about Llullaillaco and what it tells us about the Paranal skyline, read issue 151 of the Messenger.