Pluto has an active surface, according to a new analysis of distinctive polygons on the dwarf planet. This new finding could show that the body possesses icebergs that float on nitrogen ice, slowly moving over time.
The unusual features are found in the Sputnik Planum region of the distant world.
The New Horizons spacecraft, which passed Pluto during the summer of 2015, recorded images revealing a series of polygons thick in the middle and thin around their edges, creating a quilt-like pattern.
"Imagine oatmeal boiling on the stove; it doesn't produce one bubble for the entire pot as the heated oatmeal rises to the surface and the cooler oatmeal is pushed down into the depths, this happens in small sections across the pot, creating a quilted pattern on the surface similar to what we see on Pluto," said Alex Trowbridge of Purdue University.
Unlike a boiling pot, however, this process on Pluto takes place slowly, moving the terrain by less than an inch each year.
Astronomers believe the polygons seen on the surface of Pluto could be examples of a phenomenon known as the Rayleigh-Benard convection cells. The features each stretch 12 to 18 miles across, but like icebergs on Earth, only the tips of the features can be seen above the surface.
Pluto appears to be covered in water ice, although the Sputnik Planum sits upon a large deposit of nitrogen ice. Unlike water, however, nitrogen is not structurally sound in its solid state, and the material warps and deforms under pressure. These conditions can allow water ice to form mountain-like structures at the edge of the polygons.
Astronomers hope that by determining how these mountains of ice moved within the nitrogen deposits, they will be able to calculate the depths of the pools.
According to data collected by the New Horizons spacecraft, the material found at the Sputnik Planum is extremely young — less than 10 million years old. This tells astronomers the planet is active, and major changes have taken place there in the relatively recent past.
For a world once thought to be dead, the New Horizons spacecraft has shown the dwarf planet to be far more interesting than anyone believed.
Analysis of the unusual patterns seen on Pluto was profiled in the journal Nature.