A blue-green flash at Paranal Observatory

The green flash is a rare optical phenomenon due to the refraction produced by the Earth´s atmosphere It is typically observed at sunset or at sunrise and more likely in clear atmosphere, where the light is less scattered by the air. In very exceptional atmospheric conditions, a blue flash can be seen. The event captured in this picture taken from Paranal Observatory, clearly shows a green and a blue component. As usual, the Pacific Ocean, only 12 km away from the observatory, is covered by clouds. Cerro Paranal is a 2600 m high mountain, located in the driest area of the Atacama Desert, in the II Region of Chile. Thanks to its exceptional atmospheric conditions, Cerro Paranal is home of the Very Large Telescope (VLT), the most advanced optical-infrared ground-based astronomical facility in the world.