Venus’s pale yellow clouds may hide something surprisingly dark

A century-old mystery in Venus’s clouds just became more intriguing, as scientists calculated how strongly the unidentified material behind its dark ultraviolet patterns must absorb light. The results sharply narrow the possibilities and could help future spacecraft determine whether the mysterious substance is organic, inorganic, or something unexpected. Venus’s pale yellow clouds may hide something surprisingly dark.

Venus’s pale yellow clouds may hide something surprisingly dark Science News from research organizations Venus’s pale yellow clouds may hide something surprisingly dark Scientists have narrowed the search for the mysterious substance darkening Venus’s clouds, bringing a century-old planetary puzzle closer to being solved. (This image of the equatorial region of Venus taken by the Japanese Akatsuki probe provides striking detail of the equatorial, tropical, and extra-tropical clouds of the planet.). There, dark and bright features sweep across the planet’s upper sulfuric acid clouds.

Scientists have observed these patterns for about a century, yet the substance producing them, known as the "unknown absorber," has never been identified. Now, an international team of researchers has placed new numerical limits on what this mysterious material must be like. Using observations of Venus together with radiative-transfer modeling, the scientists estimated how strongly the liquid inside the planet’s cloud droplets would need to absorb ultraviolet and blue light to match what spacecraft and telescopes observe.

Reimagining Venus’s Clouds in the Lab The study, published in Astrobiology, examined the problem in an unusual way.