The dense haze that covers Pluto is formed by a mixture of ice with cyanide subject to very particular conditions, indicates a study carried out by researchers in France.
According to scientists from the University of Reims Champagne-Ardenne , compounds such as methane, carbon monoxide and nitrogen, abundant in Pluto's atmosphere, react to ultraviolet radiation in the presence of cyanide, which causes substances to settle on the surface of the dwarf planet.
In doing so, they become a kind of seed that allows the formation of other organic compounds that condense towards the surface, which causes the formation of mist particles.
A few years ago, observations by the New Horizons probe – which flew over Pluto in mid-2015 – gave scientists clues about how the dwarf planet's haze forms. Experts thought that because of its chemical similarity to the atmosphere of Titan, the giant moon of Saturn, the process of haze formation was similar. However, the New Horizons observation did not explain how, with slower chemistry, Pluto forms such a dense haze.
The response of the scientists from the University of Reims Champagne-Ardenne is based on simulation models of atmospheric chemistry, including the physics of particles deposited on the surface of Pluto. And he adds that if cyanide particles in Pluto's atmosphere did not interact with other organic elements, they would likely sublimate to gas again. Also, it indicates that other simple organic compounds would freeze on their own, contributing more "seed" particles that produce the characteristic haze.