A silent watcher

This Picture of the Week shows the stunning night sky over the Swedish–ESO Submillimetre Telescope (SEST) telescope at ESO’s La Silla Observatory in Chile. Until its retirement in 2003, SEST used its 15-metre main dish to observe the cold gas clouds where stars form. Now the telescope, perching at 2375 metres altitude, watches silently over the landscape of the Atacama Desert.

While SEST stands in one of the darkest places on the planet, the sky itself isn’t completely black — rather the opposite! Here, besides thousands of stars, the picture features shades of red and green across the sky — an atmospheric phenomenon called airglow. In the bottom-left part of the sky we can see a portion of the band of the Milky Way, our home galaxy, and in the top half, two cloud-like structures that look like galactic fireworks. These are the Large and Small Magellanic Clouds, two dwarf galaxies that orbit the Milky Way, trapped by its gravity. They are visible to the naked eye and have been known since ancient times to indigenous peoples in the Southern Hemisphere, who often compared them with water ponds or even animals like pigs or tapirs.

In this picture, there is even a shooting star coming by to say hello to SEST. Can you spot it in the sky?