Here's a space discovery of the day: NASA's Cassini has detected plastic on Saturn's moon. This is the first time that propylene has been discovered anywhere else other than Earth. 

The finding also marks the first chemical discovery observed by the Cassini Saturn orbiter's composite infrared spectrometer. There have been other chemicals observed on Titan before but none of them were propylene, given that titan's atmosphere has a high concentration of methane, and propylene is produced when we break down hydrocarbons like methane.