Out in the farther reaches of our Solar System, there sits the icy dwarf planet, Pluto. Seemingly forsaken, it is not alone — as in myth, so in life, Pluto is accompanied by Charon, named after the ferryman of Greek legend whose job was to take the souls of the dead across the river Acheron (or the Styx) to Hades. Fittingly, Charon the moon is besmirched with a murky red color at its north pole reminiscent of dried blood — as if the icy terrain were a frozen battlefield. The region is even named Mordor Macula. But scientists aren’t sure exactly how it got its gory hue. Now, a new theory upends our ideas of what Charon is made up of — and its ties to Pluto.
