ALMA radio telescopes. Time-lapse footage of the bright star Sirius and part of the Milky Way in the night sky over the Atacama Large Millimeter Array (ALMA) radio telescopes in the Atacama Desert, Chile. This array of 66 radio telescopes is located at an altitude of 5000 metres on the Chajnantor plateau of the Andes. It is operated by the European Southern Observatory (ESO). The movements of the telescopes during observations are carefully co-ordinated. Data from the separate telescopes is combined by interferometry, making it one of the most powerful and complex observatories in the world. This footage also includes red and green airglow towards the end of the clip. Filmed in April 2016.