Inside Pluto

Just what is this far-flung celestial body actually made up of?

Rocky core

At Pluto’s heart is a dense, rocky core that is said to be 1,700 kilometres (1,056 miles) in diameter. That makes up some 70 per cent of the dwarf planet’s overall diameter of 2,370 kilometres (1,473 miles).

On the surface

With minimal air pressure Pluto is certainly no place for humans. The surface has valleys, frozen nitrogen gas plains, craters up to 260 kilometres (160 miles) in diameter and mountains that are as tall as three kilometres (1.9 miles).

A covering shell

Methane and nitrogen frost coat Pluto’s surface, and there is a possibility that it is creating a shell across the dwarf planet. New Horizons showed that water ice was widespread across the surface.

What an atmosphere!

As ice thaws, it evaporates into the thin atmosphere as molecular nitrogen with a hint of methane and carbon monoxide. The atmosphere can freeze and fall as snow as it moves away from the Sun.

Mantle of ice

It is likely that the core is surrounded by a mantle of water ice, which could be as thick as 180 kilometres (112 miles). In fact, Pluto could be harbouring a liquid ocean insulated by a layer of gas from an ice covering.