NASA releases new 'head-scratcher' images of Pluto

"Seeing dunes on Pluto - if that is what they are - would be completely wild, because Pluto's atmosphere today is so thin," said William B. McKinnon, a GGI deputy lead from Washington University, St. Louis, in a news release. "Either Pluto had a thicker atmosphere in the past, or some process we haven't figured out is at work.