During a flyby, NASA's New Horizons spacecraft snapped a photo of Pluto with a massive heart. It's not like a human heart, however, but a heart-shaped region made of nitrogen ice. Now, scientists have provided information on how it was formed and how it got there.
The massive heart lies in Pluto's 1,200-mile across region called Tombaugh Regio and the 1000-km-wode western lobe of the heart has been dubbed Sputnik Planum. The region has darker equatorial terrains as borders but the interior appears featureless, NASA reports in 2015.
However, in a new study published in the journal Nature, scientists have discovered that the heart shape is to a large degree created by highly volatile nitrogen ice. They analyzed data and observations collected during NASA's Horizons flyby to create an environmental simulation that details the history of the Dwarf planet in the last 50,000 Earth years.
The scientists suspect that the size of the massive heart on Pluto's surface may hint that there was a vast reservoir of nitrogen ice beneath the planet's surface. However, the new model shows that there is no deep ice reservoir present.
"This happens because of nitrogen's solid-gas equilibrium. At the bottom of the basin the pressure of the atmosphere - and therefore of gaseous nitrogen - is higher, thus the frost temperature is higher than the outside. As a result, nitrogen prefers to condense into ice there," explained study author, Tanguy Bertrand, at the Université Pierre et Marie Curie, France.
"Carbon monoxide ice, which is similarly volatile to nitrogen, was also found in be entirely sequestered with nitrogen in the basin. Methane ice, which is much less volatile at Pluto's temperatures, is not restricted to the Sputnik Planum glacier like nitrogen and carbon monoxide," he said, adding that the study's model shows that pure methane frosts cover both hemispheres seasonally.
However, the researchers said that the glacier will eventually change shape, in the long run, becoming large and then shrinking just like a beating heart.