Icy Pluto may have blue sky

It turns out that Pluto may have more going for it than even the scientists of New Horizons might have figured. Photos from the dwarf planet have revealed mountains and glacier flows and dynamic terrain galore. Now, it seems that the distant world may have blue skies.

The latest photos of Pluto’s atmospheric haze — now in color — show a gorgeous blue hue.

“Who would have expected a blue sky in the Kuiper Belt? It’s gorgeous,” Alan Stern, New Horizons principal investigator, said in a statement.

While the haze is probably made up of red or gray particles, the blue tint means they are small enough to scatter blue light in the same way our own sky does. The particles are probably a bit bigger than the nitrogen that gives our sky its color, but they are in the same ballpark.

Enter tholins, which you’ve probably heard of at least once during this epic year of Plutonian science. These tar- or sootlike particles, which are formed when nitrogen and methane break apart in ultraviolet light and recombine in new, complex macromolecules, are responsible for the red coloring on Pluto’s surface — and probably for the great red spot on its moon Charon, as well. It’s most likely these particles, formed high up in Pluto’s atmosphere, that create the brilliant blue scatter.

Blue skies aren’t the only cool find announced recently: NASA scientists also report finding small patches of exposed water ice. There’s ice all over the chilly planet, but in most places any H2O is covered up by ices made from other molecules.