Astronomers have found a potential sign of life high up in Venus’ atmosphere: hints that strange microbes may be living in the sulfuric acid-laden clouds of the greenhouse planet.
Two telescopes in Hawaii and Chile detected in the dense Venusian clouds the chemical signature of phosphine, a noxious gas that on Earth is only associated with organic entities, according to a study published today in the journal Nature Astronomy.
Several outside experts, and the study authors themselves, agreed that this is tempting, but said it is far from the first proof of life on another planet. They noted that it does not meet the standard of “extraordinary claims require extraordinary evidence” set by the late Carl Sagan, who speculated about the possibility of life in the clouds of Venus in 1967.
“This is not hard evidence,” said study co-author David Clements, an astrophysicist at Imperial College London. “It is not even circumstantial evidence, but it is an indication that there is something there.”
As astronomers plan to search for life on planets outside our solar system, an important method is to look for indicators that can only be made by biological processes, so-called biological signatures. The astronomers decided to look that way at Venus, the closest planet to Earth. They looked for phosphine, which is three hydrogen atoms and one phosphorous atom.
On Earth, there are only two ways phosphine can be formed, the study authors said. One is in an industrial process. (The gas was produced for use as a chemical warfare agent in World War I.) The other way is as part of some kind of little-known function in animals and microbes. Some scientists consider it a waste product, others do not.