Wow. NewScientist (12 March 2016, paywall) first caught my attention on this one:
Images released publicly by the New Horizons team have already shown off Pluto’s surprisingly complex atmosphere, featuring many layers of haze rising above icy mountains. But in emails and images seen by New Scientist, researchers on the mission discuss the possibility that they have spotted individual clouds, pointing to an even richer atmospheric diversity.
The first sign of clouds came on 13 September last year, a few days before the public release of the haze pictures. Will Grundy of the Lowell Observatory in Flagstaff, Arizona, sent an email to a discussion list dedicated to analysing New Horizons results about Pluto’s atmosphere. “There’s a few fairly localized low-altitude features just above the limb that I’ve drawn lame arrows pointing to, but also a few bright cloud-like things that seem to be above and cutting across the topography in the circled area,” he wrote. Grundy had spotted features in the haze on the edge – or “limb” – of Pluto that seemed to stand out from the distinct layers. But intriguingly, he had also seen a bright feature crossing different parts of the landscape, suggesting it was hovering above.
But this isn’t actually new. Back in 2009 ScienceNews published speculation (must pay to see the entire article) that clouds on Pluto could exist:
Clouds in Pluto’s atmosphere may be composed of tiny frozen spherules of nitrogen or carbon monoxide, rather than snowflake-like clumps of tiny particles as previous research had suggested, new analyses suggest.
Information about Pluto’s atmosphere is, like that atmosphere itself, exceedingly thin because no space probes have yet visited there. So most speculations about the dwarf planet’s atmosphere stem from analyses of light passing through that tenuous shroud on the rare occasions when Pluto passes in front of a distant star, says Pascal Rannou, a planetary scientist at the University of Reims in France.
Discovery.com covers the more recent news:
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.
“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.
Fabulous!
