Pluto's Secret Revealed: Scientists Find Ocean Hiding Beneath Pluto's Heart

A new study has found that Pluto has a heavy heart, literally. And this is because there is a slushy underground ocean hiding beneath the planet's icy crust. The existence of this could explain the gravitational anomaly that has been happening in the dwarf planet.

Last year, NASA's New Horizons spacecraftrevealed a photo of Pluto's heart-shaped feature. Located just above the icy planet's equator, the left lobe appeared perfectly shaped while the other side appeared to be less defined.

The left lobe was called Sputnik Planitia, named after Earth's first artificial satellite. Sputnik Planitia was thought to be an enormous impact crater with quite a bizarre feature ---it has a strange orientation, and it aligns almost exactly with the tidal axis between Pluto and its large moon, Charon. Until now, nobody can explain the almost perfect alignment.

As per the first study lead by James Keane, a doctoral student at the University of Arizona's Lunar and Planetary Laboratory, the Pluto is lying on its side because the crater is loaded with nitrogen ice as thick as six miles.

"Loading of volatile ices within a basin the size of Sputnik planitia can substantially alter Pluto's inertia tensor, resulting in a reorientation of the dwarf planet of around 60 degrees with respect to the rotational and tidal axes," the study said.

But why is it perfectly aligned?

"The New Horizons data say it's not only opposite Charon, but it's really close to being almost exactly opposite," Richard Binzel, professor of earth, atmospheric and planetary sciences at MIT, said in a press release. "So we asked, what's the chance of that randomly happening? And it's less than 5 percent that it would be so perfectly opposite. And then the question becomes, what was it that caused this alignment?" he added.

The scientists suggest that this would not happen unless there is an extra mass interacting with the tidal forces of Pluto and Charon.

The second study strengthened the theory.

According to Francis Nimmo, a professor of Earth and planetary sciences at the University of California, Santa Cruz, lead author of the second study, the impact that created the crater could have weakened the crust overlying a buried ocean, causing some of the water to rise close to the surface. And this resulted to the gravitational anomaly.

"Our view is that 40 kilometers' thickness of nitrogen ice is not that likely," Nimmo told Space.com. "So if you want to have another source of dense material down there, then water seemed like a very natural explanation, because water is a lot denser than ice."

Without an underground ocean heaving beneath it, the nitrogen ice would have to be 25 miles (40 kilometers) thick for there to be enough mass to roll the planet over, Space Flight Insider notes.