Pluto is surrounded by a haze of blue.
The New Horizons space probe has sent back color photos of the dwarf planet on the edge of our solar system, and Pluto is ringed by blue—courtesy of a cloud of soot-like particles.
These particles aren’t the same type that make the skies over Earth look blue to our eyes. “A blue sky often results from scattering of sunlight by very small particles,” said New Horizons science team researcher Carly Howett in a NASA press release. “On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger—but still relatively small—soot-like particles we call tholins.”
The Pluto particles are red and gray, but it’s possible that, if you were standing on the surface of Pluto, the sunrise would look blue to you.
NASA has also found more evidence of the other type of of blue expanse—water—on both Pluto and Mars. There are exposed stretches of water ice on Pluto, and on Mars there’s evidence that what are now dry craters were once lakes.
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