Boffins baffled as newest Pluto pictures reveal land of mountains and dunes

NASA has released new photos which show mountains, possible dunes and multiple layers of haze on the dwarf planet Pluto. The images were taken by the New Horizons spacecraft as it swept past the distant body in July. Scientists say they reveal an even more diverse landscape than they had previously imagined. In one picture, dark ancient craters border much younger icy plains. Dark ridges also are visible that some scientists speculate might be dunes. One outer solar-system geologist, William McKinnon of Washington University in St. Louis, said if the ridges are, in fact, dunes, that would be “completely wild” given Pluto’s thin atmosphere.

If an artist had painted this Pluto before our flyby, I probably would have called it over the top — but that’s what is actually there.

Alan Stern, New Horizons’ principal scientist

The jumble of mountains, on the other hand, may be huge blocks of ice floating in a softer, vast deposit of frozen nitrogen. After several weeks of collecting engineering data from New Horizons, scientists started getting fresh Pluto pictures last weekend. The latest images were released Thursday. Besides geologic features, the images show that the atmospheric haze surrounding Pluto has multiple layers. What’s more, the haze crates a twilight effect that enables New Horizons to study places on the night side that scientists never expected to see. Monday marks two months from New Horizons’ close encounter with Pluto on July 14, following a journey from Cape Canaveral, Florida, spanning 3 billion miles and 9½ years.

Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work. It’s a head-scratcher.

William McKinnon of Washington University in St. Louis

Science Pluto