One of the great discoveries of the flyby was the discovery of an ocean beneath the icy hull enclosing Pluto. The ice sheet was thin at a location near the equator, about the size of Texas, known as Sputnik Planitia, which helped the researchers to notice Pluto's weird topography and point to the existence of the ocean.
But that caused a mystery. Given the age of Pluto, which is estimated at 4.4 to 4.6 billion years, the ocean should have frozen hundreds of millions of years ago. And instead of forming a bubble, the ice bowl should be flattened over the frozen ocean.
The most likely scenario is gas between the ocean and the ice shell, which later acts as an insulating agent. This layer of gas, probably methane, which was formed during the formation of the dwarf planet in the rocky core of Pluto, would be thick and have a low thermal conductivity.
The researchers believe that the layer exists in the form of gas hydrates, where water molecules form lattice-like cages that trap gas molecules, the study said.
And this insulating gas layer would have meant that the ice tray would have taken more than 1 billion years to achieve a uniform thickness.
Pluto's atmosphere is rich in nitrogen and low in methane. The gas layer between the ice shell and the ocean could explain where the methane is located.
The impact extends to other icy ocean worlds in our solar system, such as Jupiter's moon Europa and Saturn's moon Enceladus, as well as exoplanets. If insulating gas layers prevent the oceans from freezing beneath the surface, there could be a plethora of ocean worlds out there, the researchers said.
"This could mean that there are more oceans in the universe than previously thought, making the existence of extraterrestrial life more plausible," said Shunichi Kamata, study author and adjunct professor at the Institute of Earth and Planetary Sciences at Hokkaido University in Japan in a statement.