It what could soon be called "Cloudgate," "leaked" emails appear to discuss structures in Pluto's already hazy atmosphere as clouds, based on a March 4 article in New Scientist.
The picture above shows sections of an image attached to an email sent by Southwest Research Institute scientist John Spencer, in which he noted particularly bright areas in Pluto's atmosphere within a New Horizons image.
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"In the first image an extremely bright low altitude limb haze above south-east Sputnik on the left, and a discrete fuzzy cloud seen against the sunlit surface above Krun Macula (I think) on the right," Spencer wrote.
While it was quickly determined after New Horizons' July 2015 flyby that Pluto is enveloped in a complex atmosphere comprising layers of blue-tinted haze, individual clouds couldn't be resolved. That may have changed as high-resolution data continues to arrive on Earth from the still-moving spacecraft, now 1.9 AU - or approximately 180 million miles - past Pluto.
Unlike clouds on Earth, Plutonian clouds wouldn't be composed of water - they would likely be made of particles of nitrogen ice along with methane and other compounds.
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Clouds are different from haze in that haze is a very diffuse and widespread suspension of particles while clouds are more concentrated and regional, and usually much less long-lived.
If this is true this would be the first time actual clouds have been identified on Pluto, although no official confirmation or findings have yet been announced or published by either the New Horizons team or NASA.
Read more on New Scientist.