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Pluto’s Frozen ‘Heart’ Has Been Explained

Photo from NASA

Pluto’s ‘heart’ isn’t exactly the Valentine’s-worthy kind, scientists reveal in a new study.

The New Horizons spacecraft took a close-up image of the former ninth planet during its July 13, 2015 fly-by at 476,000 miles away. NASA released the now-famous image, which showed a light formation that resembled a heart covering the Sputnik Planum region of Pluto.

The heart, measuring some 1,200 miles across, was named Tombaugh Regio after Clyde Tombaugh, the American astronomer who first discovered Pluto in 1930, CNET reports.

NASA said last year that, “the heart borders darker equatorial terrains, and the mottled terrain to its east (right) are complex. However, even at this resolution, much of the heart’s interior appears remarkably featureless – possibly a sign of ongoing geologic processes.”

Using simulations, researchers Tanguy Bertrand and François Forget at the University of Paris tracked geological movements over 50,000 years in both the past and the future to see what might have formed the heart and how it might change, Astronomy Magazine reports.

The heart is actually a massive glacier containing mostly frozen nitrogen, Bertrand said. Sputnik Planum is a very deep basin, with atmospheric pressure at its base greater than that on higher ground. This means nitrogen can condense out of Pluto’s atmosphere at higher temperatures, making it easy for nitrogen deposits, carbon monoxide and methane to accumulate in the basin. This forms a “permanent reservoir of ice,” according to Bertrand, acting as a “cold trap.”

Scientists had originally thought that under the dwarf planet’s layers was nitrogen ice. But according to new data from New Horizons, and these simulations, there’s a new best guess, the San Francisco Gate reports.

There appears to be no nitrogen ice under the surface, but instead a surface that’s so cold that carbon monoxide becomes rock-solid while methane frosts at the dwarf planet’s polar caps expand and recede in a cycle. The same simulations were used to predict that these frosts will soon disappear in the next ten years, but the Sputnik Planum glacier is large enough to ignore seasonal changes, flowing and contracting. This means that the glacier – and the heart – is expected to stay intact for good.

The study was published in the journal Nature.


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