Scientists Found Phosphine on Venus—A Possible Hint of Life

Astronomer Jane Greaves of Cardiff University was alone in her office when she saw the signal: a fingerprint from the molecule phosphine, hanging out in data she’d taken of Venus’ atmosphere back in 2017.You’ve probably never heard of phosphine, and so don’t know why its existence on a nearby planet would stun an astronomer, as it did Greaves. But some scientists think phosphine—a humble pyramid of three hydrogen atoms bonded to a phosphorus—may be a useful biosignature: a sign, if you see it on a solid-surface terrestrial planet, that life might live there.

It was possible, though unconfirmed, that Greaves had just caught the first glimpse of alien beings. She wandered around in a daze.

The hour was late and everyone else had gone home. “There wasn’t really anyone to tell,” she says. Cautious of jumping to conclusions, she stifled her excitement and commanded herself to do normal things, to focus on the business of living. So she left work and went to the grocery store. “Must find food, must do something sensible, must not crash the car,” she recalls telling herself on that evening in late 2018.

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Sign up for our Longreads newsletter for the best features, ideas, and investigations from WIRED.“Being British, I had to buy the ingredients for curry,” she adds. A celebration.She spent the next few days checking that she hadn’t made a mistake. The signal, which sure looked like phosphine, persisted. And today, after many more months of data gathering and analysis, she and a team of colleagues made the official announcement: There appears to be phosphine on Venus, and so far they’ve found no explanation for why it might be there—except as a result of Venusian life.That doesn’t mean there is life on Venus. Some nonbiological process unknown on Earth might have churned the molecule into existence. Humans have, after all, cried “Aliens!” because of suspicious chemistry before. But while there’s much followup work to be done—many complications, confirmations, or denials that could and probably will come—it’s also possible today’s the day humans are introduced to the ultimate other.

Image of Venus, observed in the 365nm waveband by the Venus Ultraviolet Imager (UVI) on board the Akatsuki probe. The observations were made on 6 May 2016, when the spacecraft saw the whole planet illuminated.Photograph: J. Greaves/Cardiff University
On its hot, horrid face, the idea that Venus might make a nice home sounds absurd. Its surface is more than 800 degrees Fahrenheit. Its pressure is akin to that found 3,000 feet under the earthly ocean. It’s very metal there. So metal you could melt lead. So metal that human-sent spacecraft melt and crumple within hours of landing.

But scientists have speculated about strange life on Venus for decades. In part that’s because the planet was not always thus: It may once have boasted an ocean. Life could have arisen back when the neighborhood was nicer and evolved as conditions transformed the planet into a literal hellscape. Evolved, that is, to live in a chiller part of the planet: the clouds, more than 30 miles above the surface, where the pressure eases up and the temperature dips into the 80s.