The New Horizons spacecraft discovered that the temperature of Pluto’s atmosphere is much lower than the previous estimates. The cooling mechanism is still a mystery, although modeling by Xi Zhang and his team suggests that a chemical reaction, originating from haze particles in the atmosphere, dominates heating and cooling by radiative equilibrium with atmospheric gas. The team suggests that Pluto will appear much brighter than a blackbody in mid-infrared wavelengths, a prediction that could be tested by the James Webb Space Telescope. READ MORE »