On such worlds, “as far as we know, only life can produce phosphine,” said Dr. Sousa-Silva. He has long studied gas, on the theory that finding it emitted by rocky planets orbiting distant stars could be proof that life exists elsewhere in the Milky Way.
Here on Earth, phosphine is found in our gut, badger and penguin feces and some deep sea worms, as well as other biological environments associated with anaerobic organisms. It is also extremely poisonous. The military used it for chemical warfare and it is used as a fumigant on farms. On the television show “Breaking Bad”, the main character, Walter White, manages to kill two rivals.
“You don’t really understand where such things come from, how they form,” said Matthew Pasek, a geoscientist at the University of South Florida in Tampa. “We’ve seen it associated with where microbes are, but we haven’t seen a microbe make it, which is a subtle, but important difference.”
Dr. Sousa-Silva was surprised when Dr. Greaves said she had detected the phosphine.
“That moment plays a lot in my mind, because I took a few minutes to consider what was going on,” he said.
If there really was phosphine on Venus, he believed there could be no obvious explanation other than anaerobic life.
“What we find circumstantially also makes complete sense with what we know thermodynamically,” he said.
The team needed a more powerful telescope, and the scientists subsequently used the Atacama Large Millimeter Array in Chile in March 2019.