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Icy Pluto

StarDate: 
December 26, 2016

The most prominent feature on Pluto is like a cold lava lamp, with big blobs of ice slowly bubbling to the surface.

Sputnik Planum looks like a white heart. It’s bigger than Texas and Oklahoma combined, and it’s filled with frozen nitrogen. The ice looks like it’s pieced together like the tiles on a floor, with each tile anywhere from about 10 miles to 30 miles wide.

Researchers used computer simulations to try to decipher why the feature looks that way. They concluded that Sputnik Planum is a big impact crater filled with a layer of frozen nitrogen that’s several miles thick. And none of that ice appears to be more than about a million years old.

Ice at the bottom of the ice layer is warmed by the faint heat of Pluto’s interior. Big blobs of the warmer ice rise through the cooler ice above — at a rate of an inch or two a year. So it takes half a million years or so for a given blob to reach the surface. At the surface, the blob cools and drops back into the icy depths — keeping Pluto’s “lava lamp” going.

Other simulations have found something even more remarkable: A global ocean of liquid water appears to lie beneath Pluto’s icy crust. A study found that the ocean could be dozens of miles deep, and as salty as the Dead Sea here on Earth. Some of the water could occasionally bubble up through cracks in the crust, creating fresh ice on Pluto’s frigid surface.

We’ll talk about a “beanie cap” of ice on Pluto’s largest moon tomorrow.

 

Script by Damond Benningfield

 

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