A new study has found that the gases surrounding Pluto are fading away, returning to the ice as the dwarf planet drifts away from the sun.
Pluto’s atmosphere is composed largely of nitrogen with a few drops of methane and carbon monoxide. As temperatures drop at the surface, this appears to cause nitrogen to freeze again, causing the atmosphere to evaporate.
The evaluation was conducted using a distant star as a backlight for telescopes on Earth, to get a look at what’s happening on Pluto. It is a tried and tested observational technique widely used in astronomy.
“Scientists have used astrology to monitor changes in Pluto’s atmosphere since 1988,” says planetary scientist Eliot Young of the Southwest Research Institute (SwRI) in Texas. “The New Horizons mission obtained an excellent density profile from its 2015 flyby, consistent with a doubling of the atmosphere. The atmosphere of Pluto has been around every decade, but our observations for 2018 do not show a continuation of this trend from 2015.”
Pluto’s atmosphere consists of ice evaporating at the surface, with small changes in temperature leading to large changes in the bulk density of the atmosphere.
It currently takes the dwarf planet “248 years on Earth” to make one orbit around the sun, in about 30 astronomical units (AUs) from the sun – 30 times the distance between the Earth and the sun.
However, this distance is increasing, causing less sunlight and lower temperatures for Pluto. The increase in atmospheric density observed in 2015 is likely due to thermal inertia – residual heat trapped in nitrogen glaciers that has a delayed reaction to the increasing distance between Pluto and the Sun.
Pluto may not be considered a planet anymore – it’s still a source of some controversy among experts – but it remains very much an important planetary body for astronomers.
And in recent years, astronomers have been able to confirm that there are snow-capped mountains on Pluto, and liquid oceans beneath its surface – two discoveries that could tell us more about how the dwarf planet’s atmosphere works.
The 2018 observations made use of a “central flash”, which indicates that the telescopes in use were looking directly at Pluto while calculating atmospheric measurements, increasing their reliability.
The results were reported at the annual meeting of the American Astronomical Society for Planetary Sciences.
Source: Science Alert