Astronomers have detected phosphine gas on Venus, which they believe could be created by life

By Rachel DeSantis
September 14, 2020 01:21 PM
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Venus
SSV, MIPL, Magellan Team, NASA

A group of astronomers have detected trace amounts of a highly toxic gas on Venus, a “promising” sign that Earth’s closest neighbor may be home to possible life.

In an article published in Nature Astronomy on Monday, the astronomers said that phosphine (PH₃) gas has been found in Venus’ atmosphere — and according to one of the writers of the study, one of the best explanations for its creation is life.

“As far as we can tell, only life can make phosphine,” Clara Sousa-Silva, molecular astrophysicist at Harvard University, told The New York Times. “We know that it is an extraordinary discovery. We may now know just how extraordinary without going back to Venus.”

The study says that on Earth, phosphine is produced biologically, and it’s “uniquely associated” with human activity or microbial presence, even in an oxidizing environment.

Venus’ environment is significantly harsher than that of Earth; its temperatures can melt lead, and its atmosphere is so thick it would crush a human, according to NASA. It’s also inhospitable for human life, as it’s dehydrating and hyperacidic, the study says.

However, the study claims that there is no known chemical process able to explain phosphine’s presence on Venus, and therefore it must be produced in a way “not previously considered plausible” for the planet’s conditions.

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The Times reported that, using telescopes, scientists found that Venus had thousands of times more phosphine than Earth, and the light in Venus’ environment constantly breaks it down, meaning there must be something continuously replenishing it.

The researchers’ models reportedly found that volcanic activity and lightning on the planet wouldn’t enough to keep adding more — but living things might be.

“I should emphasize that life, as an explanation for our discovery, should be, as always, the last resort,” Sousa-Silva told Reuters. “This is important because, if it is phosphine, and if it is life, it means that we are not alone. It also means that life itself must be very common, and there must be many other inhabited planets throughout our galaxy.”

The study says that there are other parts of the Solar System that have phosphine, but only in the atmospheres of giant planets, in which cases it is produced “in deep atmospheric layers at high temperatures and pressures, and dredged upwards by convection.”

On the solid surface of a rocky planet like Venus, the gas would be quickly destroyed before making it to the interior.

“This could be unknown photochemistry or geochemistry, or possible life,” the study says. “Information is lacking — as an example, the photochemistry of Venusian cloud droplets is almost completely unknown.”

The study acknowledges that the detection of phosphine is “not robust evidence for life” — only for “anomalous and unexplained chemistry,” something other scientists stressed to the Times.

Still, the discovery will make waves, and, the study’s authors hope, will ramp up efforts to further research into the topic.

“This is an astonishing and ‘out of the blue’ finding,” Sara Seager, planetary scientist at the Massachusetts Institute of Technology and one of the paper’s authors, told the Times. “It will definitely fuel more research into the possibilities for life in Venus’ atmosphere.”