A new study by an international group of astronomers suggests that there could be indicators of life on an unexpected planet: Venus.
The team identified indicators of a compound called phosphine in the clouds of Venus, which has previously been identified as a potential biomarker for life. This stinky and toxic gas is found in Earth’s atmosphere at low levels, but finding it on another planet is groundbreaking as it is primarily produced by anaerobic (non-oxygen-reliant) bacteria.
Phosphine could also possibly be produced by non-biological processes such as lightning strikes, sunlight, or volcanoes, but these would only produce very small amounts of the gas. The finding of 20 parts of phosphine per billion sounds small but is actually relatively large, and therefore could be indicative that life may exist there.
The clouds of Venus are a strange and seemingly inhospitable location, composed primarily of sulfuric acid which obscures most of the surface when seen from orbit. The clouds are so thick that they keep in heat and make Venus the hottest planet in the solar system on its surface, even though Mercury is closer to the sun.
Despite the hellish environment, the idea that microbes could exist in the Venusian atmosphere has been suggested before, although it was generally considered an outlandish possibility.
The striking new finding, published today in Nature Astronomy, was confirmed with two different instruments to ensure that it wasn’t just a fluke. The first observations were made with the James Clerk Maxwell Telescope (JCMT) in Hawaii, which saw absorption on the wavelength associated with phosphine, meaning it is likely but not 100% confirmed that there is phosphine there. These findings were then confirmed by the Atacama Large Millimeter Array (ALMA) observatory in Chile.
“To our great relief, the conditions were good at ALMA for follow-up observations while Venus was at a suitable angle to Earth,” team member Anita Richards of the UK ALMA Regional Centre and the University of Manchester said in a statement.
“In the end, we found that both observatories had seen the same thing — faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below,” added Professor Jane Greaves of Cardiff University, leader of the research team.
Greaves also said she was shocked by the potential ramifications of the research: “This was an experiment made out of pure curiosity, really — taking advantage of JCMT’s powerful technology, and thinking about future instruments. I thought we’d just be able to rule out extreme scenarios, like the clouds being stuffed full of organisms. When we got the first hints of phosphine in Venus’ spectrum, it was a shock!”
This discovery is groundbreaking in our understanding of our Solar System, according to Professor Emma Bunce, President of the Royal Astronomical Society: “A key question in science is whether life exists beyond Earth, and the discovery by Professor Jane Greaves and her team is a key step forward in that quest. I’m particularly delighted to see U.K. scientists leading such an important breakthrough — something that makes a strong case for a return space mission to Venus.”
Bunce and other curious scientists may soon get their wish, as NASA is considering sending a mission called VERITAS to Venus to investigate the planet’s geology and volcanic activity. A decision will be made about the future of this proposal next year.
