Scientists Model the True Darkness of Venus’s Mysterious UV Absorber

Scientists have found that Venus' clouds absorb ultraviolet light efficiently, with a peak absorption at 375nm, which drops off sharply at higher wavelengths. The study, published in Astrobiology, uses high-resolution reflectance data from the Akatsuki spacecraft to calculate the absorption coefficient of the material in Venus' clouds. The results suggest that the material is an extremely efficient light-absorption molecule, possibly an organic one. The study differentiates between scattering and absorption, showing that aerosolized particles appear brighter than clumped ones, explaining the color difference.

• The authors stripped away the effects of scattering, gas absorption, and particle sizes to back-calculate the absorption coefficient.
• They found an absorption peak at 375nm, which drops off precipitously at higher wavelengths.
• The peak absorption level is exceptionally high, indicating an efficient light-absorption molecule.
• The study suggests that the material is likely an organic molecule, as inorganic compounds cannot meet the necessary absorption numbers.
• The data shows a sharp drop-off around 455nm, which would not happen if the material were made up of simple "red oils."

This finding challenges previous assumptions about the composition of Venus' clouds and supports the idea that there are organic molecules in the clouds. The study highlights the complexity of Venus' atmosphere and the need for further exploration to determine the exact nature of the UV absorber. A private mission from Rocket Lab is planned to scan Venus' clouds for evidence of life, using an Autofluorescence Nephelometer that will check for telltale signs of complex, conjugated organic molecules.

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