Venus loves keeping secrets. One of the biggest, most frustrating secrets has to do with the planet’s upper atmosphere. Something is absorbing ultraviolet light, and no one can figure out what.
A Scientific Explanation
Specific atoms and molecules absorb specific wavelengths of light, producing what’s called an absorption spectrum. Given the prevalence of sulfur compounds in Venus’s atmosphere, it seems like a safe bet that some kind of sulfur containing compound is responsible for this mysterious ultraviolet absorption.
But the absorption spectrum doesn’t match with sulfur dioxide, sulfuric acid, or any other sulfur-based chemical thus far identified on Venus. After decades of observation and research, scientists can’t reach any consensus on what the heck is going on.
A Sci-Fi Explanation
Chlorophyll is a pretty important (and pretty complicated) chemical here on Earth. It’s what makes photosynthesis possible in plants, and therefore it’s what makes life as we know it possible. And it just so happens that chlorophyll’s strongest absorption lines are in the blue part of the spectrum, not far from ultraviolet. Could Venus’s unknown absorber be a sulfur-based, chlorophyll-like chemical?
In other words, could there be something alive on Venus? Could there be some kind of alien algae drifting about in Venus’s sky? Venus’s atmosphere contains a rich mixture of chemicals, including carbon dioxide and water vapor.
Even those thick, fluffy clouds of sulfuric acid might not be dangerous to creatures that evolved to live there. Who knows? Maybe sulfuric acid is highly nutritious if you have the right biochemistry.
And if these cloud algae phosphoresce, as some species of algae do on Earth, that might explain the mystery of Venus’s ashen light.
I’m presenting these cloud algae as science fiction, but many well-respected scientists have speculated about this possibility. Even so, this idea is a bit farfetched. Odds are sulfur-based life on Venus is completely impossible.
Does Alien Life Thrive in Venus’s Mysterious Clouds from Discovery News.
Could There Be Life on Venus? from Venus Dispatches.
Solar System Bodies: Venus from NASA’s Office of Planetary Protection.
Venus Revealed: A New Look Below the Clouds of Our Mysterious Twin Planet by David Grinspoon.