Atmosphere of Triton by the ground-based observations, is slightly more abundant than methane. The abundance of methane relative to nitrogen increased by four to five times since 1986 due to the seasonal warming observed on Triton, which passed its solstice in 2001. Other possible components of the Triton's atmosphere include argon and neon. Because they were not detected in the ultraviolet part of the spectrum of Triton obtained by Voyager 2 in 1989, their abundances are unlikely to exceed a few percent. In addition to the gases mentioned above, the upper atmosphere contains significant amounts of both molecular and atomic hydrogen, which is
Atmosphere of Pluto about distance to the orbiting moon. As early as the 1940s, Gerard Kuiper searched for evidence of the atmosphere in the spectrum of Pluto, without success. In the 1970s, some astronomers forwarded the hypothesis of a thick atmosphere and even oceans of neon: according to some views of those times, all other gases that are abundant in the Solar System would either freeze or escape. However, this hypothesis was based on a heavily overestimated mass of Pluto. No observational data about its atmosphere and chemical composition existed at the time. The first strong, though indirect evidence of the atmosphere appeared