The U.S. "Cassini" spacecraft has detected small amounts of propene -- a constituent of many plastics -- in the atmosphere of Saturn's largest moon, Titan.
The U.S. space agency NASA says it is the first definitive detection of such molecules on any moon or planet other than Earth.
Propene is a molecule comprising three carbon atoms and six hydrogen atoms. It is a constituent of many plastics used to make storage containers and other products.
Methane is the most common component of Titan's hazy atmosphere, after nitrogen.
Sunlight drives reactions that break apart the methane, allowing the fragments to form larger hydrocarbon molecules such as propene, propane, and ethane.
Based on reporting by AP and the BBC