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Pluto's hazy atmosphere keeps its surface icy cold

Image released by NASA in Oct. 2015 shows a haze surrounding Pluto. Photo: NASA/JHUAPL/SwRI

Pluto's thick hazy atmosphere may be responsible for its temperature of -203ºC, according to a study published this week in Nature.

How it works: Hydrocarbon particles created in chemical reactions in Pluto's upper atmosphere group together as they fall toward the surface and are "transformed into thick layers of haze," Alexandra Witze writes in Nature. Haze doesn't block light from the the sun, but it is able to cool down and heat up the atmosphere.