Pluto shows the frozen plains of its 'heart' in stunning flyover animation

NASA has released a new image of Pluto's surface, revealing the icy plains that make up part of the "heart" first spotted in earlier images.

Now informally named "Tombaugh Regio" (Tombaugh Region) after Clyde Tombaugh, who discovered Pluto in 1930, the "heart" is revealing strange geological features - which you can see firsthand in the stunning animation above.

New Horizons team members referred to the images as "intriguing" during a news briefing held Friday at NASA headquarters, but emphasised that we're in the very earliest days of the mission.

NASA estimates it will take 16 months to download all the data acquired during the New Horizons flyby of the Pluto system, and they can't be certain of what they're seeing until they've seen all the uncompressed images.

"This terrain is not easy to explain," Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team, said in a statement.

"The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations."

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The icy plains have tentatively been named "Sputnik Planum" (Sputnik Plain) after the Earth's first artificial satellite.

The irregularly shaped blobs are roughly 12 miles across, bordered by shallow troughs.

The region's surface seems young - probably no older than 100 million years old, the scientists said, and for all we know just days old - which means that fairly recent (or even current) geological processes smoothed out craters to create the features we see.

We can't yet be sure how those segments formed, but the team has two prevailing theories. They could be from the contraction of materials on Pluto's surface - like the cracks that form when mud dries on Earth. They could also be formed by convection, which could potentially occur on Pluto within a surface layer of frozen carbon monoxide, methane and nitrogen.

Pluto is cold, but its relatively warm interior could still cause convection to happen, producing a bubbling surface. Because Pluto's interior warmth would be so scant, NASA's team is leaning towards the first explanation.

The team also spotted dark streaks on the ice that they believe might have been formed by strong winds. But all of these features will remain mysterious until better-quality images have been downloaded.