A "rainbow" made of sulphuric acid appears in the atmosphere of Venus

Check out this amazingly beautiful optical effect — this rainbow-like feature, called a "glory," was recently captured by Europe's Venus Express orbiter. This is the first time the phenomenon, which also happens on Earth, has been imaged on another planet.

Top image: Simulated views of a glory on Venus (left) and Earth (right). Credit: C. Wilson/P. Laven.

A glory happens when sunlight shines on cloud droplets. Here on Earth that means water particles — but on Venus, that means sulphuric acid.

A "rainbow" made of sulphuric acid appears in the atmosphere of Venus

Credit: Earth Science Picture of the Day/Raquel Yumi Shida.

Unlike rainbows, which extend across broad arcs in the sky, glories are smaller, comprising a series of colored concentric rings centered on a bright core. In order to see one, an observer must be situated between the sun and the cloud particles. This is why they're often seen from airplanes or by mountain climbers above the cloud-line.

The Venus Express orbiter captured the image of a glory from a height of 44 miles (70 km) above the planet's surface.

A "rainbow" made of sulphuric acid appears in the atmosphere of Venus

The glory is about 745 miles (1,200 km) wide. These observations suggest that the cloud particles are 1.2 micrometers across, which is one-fiftieth the width of a human hair.

A "rainbow" made of sulphuric acid appears in the atmosphere of Venus

The fact that the glory is so wide indicates that the particles are fairly uniform. And the variations in brightness suggest that other chemicals are likely involved.

[ ESA ]