NASA released a brand-new close-up image of Pluto on Friday that shows the icy planes of the planet's "heart" in unprecedented detail. The heart is just one of many fascinating features on Pluto you'll see in the incredible animation below, which NASA also released on the same day.

The New Horizons spacecraft has been sending a steady stream of images and other data back to NASA since completing the most critical phase of its Pluto flyby on July 14. Experts at NASA have said all along that they are expecting the unexpected from the data gathered during this mission. And this shot, taken 48,000 miles above the heart's icy plains – shown on the left – reveals some of the first surprises from Pluto.

"This terrain is not easy to explain," said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team at NASA's Ames Research Center said in a statement. "The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations."

Informally named "Sputnik Planum" after the first artificial satellite to orbit Earth, the plane features irregular patches between fractures that are each about 12 miles across, surrounded by what appear to be shallow troughs, according to NASA.

One of the two prevailing theories to explain how these patches formed is that they are the result of materials contracting on the planet's surface — the same way that cracks in mud form as it dries and contracts here on Earth.

The other theory pins the reason on convection, meaning that materials from beneath Pluto's surface bubbled up and caused the cracks. Scientists suggest that this might have happened as a result of frozen carbon monoxide, nitrogen, and methane trapped within the surface layer getting heated up by Pluto's relatively warm interior.

Pluto's "heart" has been temporarily dubbed "Tombaugh Regio" after Clyde Tombaugh, who discovered the planet 85 years ago. As New Horizons continues to send back data over the next 16 months, there will be much more naming to do and many more scientific discoveries to be made.

"With the flyby in the rearview mirror, a decade-long journey to Pluto is over — but, the science payoff is only beginning," said Jim Green, director of Planetary Science at NASA Headquarters said in a statement. "Data from New Horizons will continue to fuel discovery for years to come."

To get you up to speed on how our view of Pluto has developed over the years so far, NASA also released this fantastic GIF earlier in the week.

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