Encircling Antu

Despite its name, ESO’s Very Large Telescope, the VLT, is not a single telescope! It is in fact made up of an array of four 8.2-metre-diameter Unit Telescopes (UTs) (one of which is shown here) and four additional, movable, 1.8-metre-diameter Auxiliary Telescopes (ATs) (three of which are visible on the right side of this image). 

Each UT has its own individual name in the Mapuche (Mapudungun) language. The star of this image is Antu (or UT1, the first of the UTs), and is pictured here sitting atop Cerro Paranal in Chile. This polychromatic image, taken by ESO Photo Ambassador Petr Horálek, also captures the beautiful colours of the cloudy night sky encircling Antu.

Many night-sky objects are visible here. Starting from the left we see the pink California Nebula, the Pleiades star cluster, the fiery river of the Milky Way, the constellation of Orion and its famous Belt, the looping Gum Nebula, the Carina Nebula and the Southern Cross. The most curious features are the green bands or stripes to the right of Antu’s enclosure. They are atmospheric gravity waves, generated by storms forming ripples in the greenish layer of Earth’s airglow in the upper atmosphere. This image also appeared in an ESOcast dedicated to Red Sprites, which can occur under similar conditions as gravity waves.