Something is rotten in the state of Charon, Pluto’s giant moon. OK maybe not rotten, exactly, but it’s just not…right.

Before the New Horizons spacecraft took a tour of the Pluto system in July, scientists guessed they might see a few interesting features on Charon — things like craters, and more craters, and maybe some notable landforms because Charon’s water ice surface is sturdy and capable of supporting dramatic landscapes. Several team members even dared to suggest that Charon would be surprisingly interesting — perhaps even more interesting than Pluto.

But overall, guesses seemed to converge on Charon being a dead, cratered husk.

“Craters were the number one thing people said we’d see on Charon,” said Amanda Zangari of the Southwest Research Institute, who conducted a survey of New