New evidence shows Pluto may have an ocean under its many mile-thick shell of ice.
In light of its frigid temperature, the non-planet appears to be warm enough, at least to “easily” have a subsurface ocean.
Beneath a 120-mile layer of ice, this said ocean could be 60 to 105 miles thick.
If this is the case, Pluto joins a list of outer solar system bodies, such as Saturn’s moons Enceladus and Titan, which are thought to hold liquid water.
If this were the case, Pluto’s heat would come via decaying radioactive nuclides, particularly potassium-40, inside rocks in the dwarf planet’s interior.
While, chances are Pluto’s surface is probably colder than -380°F, there could still be plenty of liquid-preserving heat beneath the ice cap. For an ocean to exist, Pluto’s rocks would have to be concentrated in a rocky core, with water and ice layered on the surface.
The New Horizons spacecraft will reach Pluto in 2015. At that point it will be easy enough to test whether Pluto really has such a subsurface ocean.
If, however, there is no ocean, say, Pluto would be comparatively flattened at its poles, and would contain a “fossil” equatorial bulge left over from early in the planet’s history, when the body was spinning more rapidly, say.
And if indeed there is an ocean on the former-ninth planet, the surface would show cracks made as Pluto gradually lost heat and the ice cap thickened over the course of billions of years.
That is because the freezing ice would have expanded, causing the surface to bulge upward, cracking in the process. If, however, there was only ice, and never an ocean, the cooling of the planet should have contracted the ice rather than expanded it. When formed, ice contracts as it cools, see?