In 2015, NASA’s New Horizons spacecraft took an image of Pluto showing mountain tops which wouldn’t be amiss here on Earth. Images revealed the mountains were covered in snow – or so experts thought. But a landscape with ice-covered mountains had never been seen anywhere else in the solar system other than on Earth, leading to confusion.
On Earth, thanks to the atmosphere, the higher in altitude one goes, the colder it gets.
On Pluto, however, which has a very thin atmosphere, it actually gets slightly warmer the higher in altitude due to the Sun’s solar rays.
What is known about Pluto is that there is methane in the atmosphere, where temperatures plunge to about -226 to -240 degrees Celsius.
An international team of scientists have now run climate simulations of the dwarf planet, which is more than 39 times farther out from the Sun than Earth is, to discover how these snow-capped mountains form.
They found that Pluto is rich in gaseous methane at high altitudes.
The mountains scrape the top of the atmosphere, from which the methane clings to the top of the mountains, crystallising and freezing.
At lower altitudes, there is not enough methane for ice to form, according to the study published in the journal Nature Communications.
Tanguy Bertrand, a postdoctoral researcher at NASA’s Ames Research Center and lead author on the paper, said: “It is particularly remarkable to see that two very similar landscapes on Earth and Pluto can be created by two very dissimilar processes.
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“However, the atmosphere is too thin to impact the surface temperatures, which remain constant.
“And unlike Earth’s upward winds, on Pluto, winds that travel down mountain slopes dominate.”
Dr Bertrand continued: “Pluto really is one of the best natural laboratories we have to explore the physical and dynamic processes involved when compounds that regularly transition between solid and gas states interact with a planetary surface.
“The New Horizons flyby revealed astonishing glacial landscapes we continue to learn from.”