Pluto, which lost its status as a planet years ago, is confronted with a new problem: Disappearing atmosphere. The icy dwarf celestial body, which is moving farther away from the Sun, lies over 4.8 billion kilometres away from the Earth.

Now the scientists have found that Pluto’s atmosphere is undergoing transformation. They used telescopes at multiple sites in the United States and Mexico to study Pluto’s thin atmosphere, primarily made of nitrogen, reported Space.com.

The research was carried out by the scientists at Southwest Research Institute (SwRI). They started studying Pluto after it passed in front of a star way back in 2018.

The researchers said that since Pluto is moving farther away from the Sun, its atmosphere is actually refreezing back onto its surface. Pluto is getting colder and colder, they added.

Scientists said its surface pressure and atmospheric density continued to increase due to a phenomenon known as thermal inertia. But for the past quarter century, Pluto has been receiving less and less sunlight as it moves farther away from the Sun, they added.

“The continued persistence of Pluto’s atmosphere suggests that nitrogen ice reservoirs on Pluto’s surface were kept warm by stored heat under the surface. The new data suggests they are starting to cool,” said SwRI Staff Scientist Dr. Leslie Young.

Unlike Earth, Pluto’s atmosphere is supported by the vapour pressure of its surface ices, which means that small changes in surface ice temperatures would result in large changes in the bulk density of its atmosphere. Pluto takes 248 Earth years to complete one full orbit around the Sun, and its distance varies from its closest point, about 30 astronomical units from the Sun (1 AU is the distance from the Earth to the Sun), to 50 AU from the Sun.