Scientists recreated the conditions on Saturn's moon Titan and watched molecules that shouldn't mix form stable crystals together — at around minus 179°C, polar hydrogen cyanide accepts nonpolar methane and ethane into its crystal structure, breaking one of chemistry's most familiar rules of thumb.

Scientists recreated the conditions on Saturn's moon Titan and watched molecules that shouldn't mix form stable crystals together — at around minus 179°C, polar hydrogen cyanide accepts nonpolar methane and ethane into its crystal structure, breaking one of chemistry's most familiar rules of thumb.

“Like dissolves like” is one of chemistry’s most useful shortcuts. Polar materials tend to associate with polar materials, while nonpolar compounds prefer their own kind. On Titan, at temperatures that turn water into rock and leave methane flowing as liquid, that shortcut has acquired an unusual exception. Researchers at NASA’s Jet Propulsion Laboratory exposed crystals of hydrogen cyanide, or HCN, to methane, ethane and other small hydrocarbon…