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'Completely Wild': Pluto Close-Ups From New Horizons Boggle Astro-Minds

A new set of Pluto images from New Horizons show terrain so varied it's astonishing astronomers.

A new set of images has been received from the New Horizons spacecraft, showing close-up images of Pluto taken on July 15 (and only just recently processed) while it was passing by the dwarf planet at high speed — but not so fast it couldn't see terrain so varied it's astonishing astronomers.

Related: NASA Shows Pluto Flyby Video and Picks Next Destination for New Horizons

"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," said the mission's principal investigator, Alan Stern, in a NASA release.

With wide plains, mountains and valleys, deltas implying moving liquids, and a dozen other features, Pluto has a far more complicated surface than many astronomers and geologists expected. This complexity offers a hint at Pluto's past. There may even be dunes — which implies strong winds, which no one expected to find on the dwarf planet.

"Seeing dunes on Pluto — if that is what they are — would be completely wild, because Pluto’s atmosphere today is so thin," said William McKinnon, deputy lead of the Geology, Geophysics and Imaging team. "Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work."

Related: Dark Side of the Dwarf: Backlit Pluto Captured in New Horizons' Parting Shot

More dramatic imagery of Pluto backlit by the sun also produced unexpected findings: a highly layered atmosphere that refracted light from the sun, showing in greater detail the landscape at the edge of the planet, otherwise a featureless black disc.

New Horizons is now 43 million miles past Pluto, well on its way to its next destination, an object in the distant Kuiper Belt that attracted the team's attention — and is within reach, if next year's funding proposal goes through.