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How cold is Neptuneās atmosphere near the one-bar pressure level?
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Neptune
A photograph of clouds in Neptune's atmosphere, taken by Voyager 2 in August 1989. The view is from below the planet's equator, and north is up. The Great Dark Spot (center left) is 13,000 km (8,100 miles)āabout the diameter of Earthāin its longer dimension. Accompanying it are bright, wispy clouds thought to comprise methane ice crystals. At higher southern latitudes lies a smaller, eye-shaped dark spot with a light core (bottom left). Just above that spot is a bright cloud dubbed Scooter. Each of these cloud features was seen to travel eastward but at a different rate, the Great Dark Spot moving the slowest.
At the one-bar reference level, the mean temperature of Neptuneās atmosphere is approximately 74 kelvins (ā326 Ā°F, ā199 Ā°C).1