Pluto’s atmosphere begins to freeze out as it drifts farther from the Sun

Astronomers report Pluto’s nitrogen-rich atmosphere is starting to freeze out as it moves away from the Sun, with atmospheric pressure dropping about 16% between mid-2021 and 2023. Pluto’s surface runs at roughly -382°F while the upper atmosphere sits around -333°F, conditions that favor frost formation as the air cools. Observations of ten stellar occultations from 2017–2023 show haze in the lower atmosphere settling toward lower latitudes as pressure falls. The findings, led by Amanda Sickafoose, suggest the atmosphere will not be fully frozen by aphelion (2114) but should rebuild somewhat as Pluto travels back toward the Sun. The study was published July 31 in the Planetary Science Journal.