Despite its extreme cold, the dwarf planet still appears to be warm enough to "easily" have a subsurface ocean, according to a new model of the rate at which radioactive heat might still warm Pluto's core.

And that ocean wouldn't be a mere puddle, noted planetary scientist Guillaume Robuchon of the University of California, Santa Cruz.

Rather, the ocean could be 60 to 105 miles (100 to 170 kilometers) thick beneath a 120-mile (200-kilometer) layer of ice, Robuchon said at an annual meeting of the American Geophysical Union in San Francisco earlier this week.

If so, Pluto would join a list of outer solar system bodies—such as