Of all the Saturnian moons examined by NASA’s Cassini probe, Titan is consistently the most interesting. Researchers have observed large lakes on the moon’s surface, a vortex that formed rapidly, possible hydrocarbon sand deposits, and what appears to be a solid ice shell.

This week, NASA further revealed the mysteries of Titan, announcing that propylene has been found on the moon’s surface. The hydrocarbon was detected in Titan’s lower atmosphere by the Cassini spacecraft’s infrared spectrometer.

“This chemical is all around us in everyday life, strung together in long chains to form a plastic called polypropylene,” said Conor Nixon, a planetary scientist at NASA’s Goddard Space Flight Center and lead author of a paper on the discovery published today in the Astrophysical Journal Letters. “That plastic container at the grocery store with the recycling code 5 on the bottom – that’s polypropylene.”

Though this discovery marks the first plastic ingredient to be found outside the Earth, astronomers have known for decades that Titan contains many hydrocarbons. Methane is abundant in Titan’s atmosphere, and sunlight breaks the gas down into other hydrocarbons such as ethane and propane, both of which have been confirmed on Titan in the past.

“I am always excited when scientists discover a molecule that has never been observed before in an atmosphere,” said Scott Edgington, deputy project scientist for Cassini at NASA’s Jet Propulsion Laboratory . “This new piece of the puzzle will provide an additional test of how well we understand the chemical zoo that makes up Titan’s atmosphere.”

(Image courtesy NASA)