A rainbow-like feature known as a “glory” has been seen by ESA’s Venus Express orbiter in the atmosphere of our nearest planetary neighbor—the first time one has been fully imaged on another planet.
Rainbows and glories occur when sunlight shines on cloud droplets—water particles here on Earth. While rainbows arch across the sky, glories are typically much smaller and are made up of a series of coloured concentric rings centred on a bright core. Glories are only seen when the observer is situated directly between the Sun and the cloud particles that are reflecting sunlight. On Earth, they are often seen from aircraft, surrounding the shadow of the aircraft on the clouds below.
In order for a glory to occur, the particles must be spherical and the same size. The atmosphere of Venus is thought to contain droplets rich in sulphuric acid.
Mission scientists at ESA hoped to find a glory in the atmosphere of Venus by imaging the clouds with the Sun directly behind the Venus Express spacecraft. They were successful. The glory in this image was seen at the Venus cloud tops, 70 km above the planet’s surface. It is 1,200 km wide as seen from the spacecraft, 6,000 km away.
Image Credit: ESA