(10.05.2019)

Thus Pluto had its equinox in 1988, before moving to perihelion (at 30 au) in 1989. Since then, the dwarf planet has continually moved away from the Sun to reach 32 ua in 2016, which represents a loss of 25 % of his average insolation.

Naively, a sharp fall in atmospheric pressure could be expected. In fact, the gas-ice balance of nitrogen imposes that for each degree Kelvin lost at the surface, the pressure should decrease by a factor of two.

But the exact opposite occurs.