These bright and unusually smooth spots dotting the moon's liquid methane and ethane oceans first showed up in observations by NASA's Cassini-Huygens spacecraft in 2013. At the time, astronomers were puzzled by the islands' unnerving ability to appear and disappear from observations over time, a quality that earned its enchanting nickname. Ever since, scientists have been trying to explain the mysterious phenomenon.

Now, according to a new study published in the journal Geophysical Research Letters, a team of researchers has come up with a potential answer: the islands are likely bits of porous, frozen organic solids bobbing on the surface of Titan's liquid oceans.