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

Illustration for article titled 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.

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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.

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Illustration for article titled 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.

Illustration for article titled A rainbow made of sulphuric acid appears in the atmosphere of Venus
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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.

Illustration for article titled A rainbow made of sulphuric acid appears in the atmosphere of Venus
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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 ]

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DISCUSSION

Spaceart
Ron Miller

HaloSim software enables one to recreate all manner of halo effects (sundogs, coronae, etc.) based not only on terrestrial conditions but on just about any atmospheric condition you'd care to create—such as, for instance, carbon dioxide crystal halos on Mars or ammonia crystal halos on Jupiter. I've used HaloSim a lot and its really fun.