Saturn’s moons are a hodgepodge of misfits. Iapetus looks like the Death Star from Star Wars. Tiny Pan resembles a cosmic empanada. And now something appears to be etching oddly straight lines across the icy surface of Dione.
The lines — or linear virgae, to use the proposed technical term — stretch for up to hundreds of kilometers, and yet are less than 5 kilometers wide. They all run parallel to the equator and reside only at lower latitudes. They are brighter than everything else around them and appear to be laid atop extant features such as ridges and craters, which means they’ve been emplaced fairly recently.
And it’s not clear yet how they got there.