This is one of the most spectacular sunsets I ever saw while working at ESO's Paranal Observatory in Chile.
The Atacama Desert is extremely dry, but clouds do show up sometimes. That day there were several dark clouds releasing very light rain that vaporised before reaching the ground. These wispy veils (called "virga") were lit by the golden sunset light, creating a lovely contrast with the blue sky above.
The telescopes you see here are 3 out of our 4 Auxiliary Telescopes. Each one has a 1.8 m mirror. These telescopes work together using a technique called interferometry: by combining their light we can achieve the resolution of a "virtual" telescope as large as the separation between the individual telescopes.