Pluto's landscape is so complex that Nasa scientists aren't sure how it got there, after New Horizons images could show huge field of dunes

How the dunes, craters and huge mountains on the dwarf planet could have been formed is 'a head-scratcher', say scientists

This synthetic perspective view of Pluto, based on the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto’s equatorial area, loo (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

The surface of Pluto is so complex that scientists aren’t sure how it got there, they have said, after images beamed back from New Horizons show an incredibly complex landscape.

The pictures show that the dwarf planet might have huge fields of dunes, massive nitrogen ice flows and valleys that could have formed as materials flowed over its surface. The complexity has stunned scientists —they shouldn’t be there, since the atmosphere is so thin.

“Pluto is showing us a diversity of landforms and complexity of processes that rival anything we’ve seen in the solar system,” New Horizons Principal Investigator Alan Stern said in a statement. “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.”

This 220-mile (350-kilometer) wide view of Pluto from NASA’s New Horizons spacecraft illustrates the incredible diversity of surface reflectivities and geological landforms on the dwarf planet (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Now scientists are trying to work out what happened to get the stunning range of complexity of features onto Pluto.

“Seeing dunes on Pluto -- if that is what they are -- would be completely wild, because Pluto’s atmosphere today is so thin,” William B. McKinnon, part of New Horizons’ Geology, Geophysics and Imaging team said in a statement. “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.”

Scientists have also been surprised to find that the haze in Pluto’s atmosphere has more layers than they knew. That creates a kind of twilight effect, meaning that terrain is lit up at sunset and gives them a kind of visibility that they’d never expected.

Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Last weekend, New Horizons started sending images back to Earth after its flyby in July — a process that will take a year, in all. The new pictures have enabled the New Horizons team to see Pluto in much detail than before, giving resolutions as high as 400 meters per pixel.