Illustration of phosphine molecules in Venus's atmosphere. The molecules were detected in the Venusian high clouds in data from the James Clerk Maxwell Telescope and the Atacama Large Millimeter/submillimeter Array and announced in September 2020. Geological processes on the planet cannot explain the amount of phosphine gas found. On Earth, phosphine is only created by industrial processes or microbes and therefore this discovery could point to the existence of extraterrestrial life in Venus's atmosphere.