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Pluto has a perspiration problem. Whenever it gets near the Sun, the recently demoted planet “sweats” out an atmosphere.

The sweat is caused by the sublimation of frozen nitrogen and methane on the dwarf planet’s surface. That sublimation works a little like our perspiration: cooling the planet’s surface while heating the upper atmosphere (see the press release for more). The upshot of all this is that Pluto’s atmosphere is upside down; it’s about 40 degrees warmer at the top than it is at the planet’s surface (it’s still pretty cold, at -180C).

Earlier observations indicated that this was probably the case, but what’s really amazing is that the Very Large Telescope’s CRyogenic InfraRed Echelle Spectrograph (CRIRES) is powerful enough to image Pluto’s lower atmosphere from a Chilean mountaintop.

credit: ESO