Laser vision

This image shows one of the four Unit Telescopes that make up ESO’s Very Large Telescope (VLT) at Paranal. Each of the 8.2-metre telescopes was given a name in the Mapuche language spoken by indigenous people from the Southern Chile. The Unit Telescope in this image is called Yepun, which means Venus.

The smaller telescope beside Yepun is one of four Auxiliary Telescopes that have a diameter of 1.8 metres. These can be combined with the Unit Telescopes to make the Very Large Telescope Interferometer (VLTI).

Yepun is equipped with the Laser Guide Star Facility that is caught in action in this picture. The laser beam’s colour is precisely tuned to energise a layer of sodium atoms in the atmosphere which creates a small bright spot — an artificial star. This star can be used as a reference to work out how much the atmosphere is distorting the light from actual stars — a process called adaptive optics — which helps to develop clear images.

Above Yepun you can see part of the Milky Way galaxy stretching across the southern sky. The brighter regions on the lower right correspond to the Large Magellanic Cloud and Small Magellanic Cloud — two satellite galaxies of the Milky Way.