Scientists find possible signs of life in the clouds of Venus

OF EARTH’S TWO planetary neighbours, Mars and Venus, it is Venus which shines brighter in the sky, comes closer in space, and is more similar in size and physical structure—almost Earth’s twin. But over the past 60 years it has been to Mars that science has paid the most attention. There are currently six operational spacecraft in orbit around it and two more on its surface, one of them an extremely sophisticated rover; more are on their way. Venus is observed by a single small satellite. Yet following a new discovery made with telescopes on Earth, it is Venus which arguably now looks more likely to harbour the thing that planetary science has come to care about more than anything else: life. The telescopes—the James Clerk Maxwell Telescope (JCMT) in Hawaii and ALMA in Chile—work not in visible light, but with sub-millimetre- and millimetre-wave radiation, which lies in between infrared light and radio waves. The hot depths of Venus’s atmosphere give off a fair bit of radiation at these wavelengths. The molecules in the cooler air above them absorb some of it as it passes out into space; the specific wavelengths absorbed depend on the molecules doing the absorbing. As a team of scientists from various institutions has now reported in , one of the chemicals thus revealed appears to be PH, or phosphine, a molecule composed of phosphorous and hydrogen.