Last updated May 4, 2018 at 4:43 pm
An unexpectedly colourful night sky was caught over the the La Silla Observatory in northern Chile.
The Danish telescope at La Silla is framed by the Milky Way, with red and green airglow illuminating the horizon. Click for a zoomable image. Credit: P. Horálek/ESO
This incredible photo features some of the telescopes at European Southern Observatory’s La Silla Observatory in northern Chile. In the centre of the photograph and framed perfectly by the beautiful arch of the Milky Way, sits the Danish 1.54-metre telescope.
Taken by ESO Photo Ambassador Petr Horálek, this photo peers right into the heart of the Milky Way, both the Large and Small Magellanic Clouds, the constellations of Orion (The Hunter) and the Southern Cross.
On the horizon the bursts of light from nearby towns can be seen. But one of the most remarkable sights is the red and green hues lighting up the sky in the distance. This phenomena is called airglow, the result of a complex chain of chemical reactions resulting in chemiluminescence.
As the sun’s radiation hits our atmosphere it interacts with chemicals including nitrogen and oxygen, creating a range of new molecules such as ozone. When night falls, these reaction products undergo further chemical reactions which release light and create the eerie glow.
Unfortunately the naked eye can’t see the colours of the airglow, with it appearing as just a light smudge. However to camera sensors, they appear as a vista of shimmering colour.
The La Silla Observatory happens to be in one of the best places in the world to see airglow. Located in South America, it is beneath the South Atlantic Anomaly, an area of weakened magnetic field above the Earth. This allows more particles from the sun to reach the atmosphere, resulting in a brighter airglow.
Learn more about airglow:
