The most distant dwarf planet in the solar system, Pluto, is covered with dunes of methane ice, a surprising discovery for this ultra-light planet, where it is about -230 degrees.
The atmospheric pressure at the surface of Pluto is 100,000 times lower than the Earth’s, so astronomers thought it was too weak for winds to form.
But snapshots taken by NASA’s New Horizons spacecraft in 2006, which flew over Pluto in 2015, allowed a team of researchers to discover dunes near a mountain range.
“The probable source of the dune’s grains is the methane ice carried by the winds from the mountains,” the scientists explain in an article published Thursday in the journal Science . “But we can not exclude that it is nitrogen ice.”
The winds would blow at an approximate speed of 30 to 40 km / h. The dunes themselves are spread over an area about 7 km long.
“When we first saw the images of New Horizons, we immediately thought they were dunes, which was very surprising because we knew there was not really any atmosphere” says Jani Radebaugh, co-discoverer and geology professor at Brigham Young University in the United States.
“But it turns out that Pluto, while being 30 times farther away from the Sun than the Earth, has similar characteristics to those of the Earth.”
Besides Pluto, it was already known that Mars, Venus or the great moon of Saturn, Titan, had dunes.
“We knew that everything in the solar system with an atmosphere and a solid surface had dunes, but we did not know what we would find on Pluto,” says lead author Matt Telfer, a professor at the University. from Plymouth.
Another discovery: the dunes are probably young, geologically. Scientists think they have been trained in the last 500,000 years.
On Earth, the formation of sand dunes is only possible with strong winds, explains Eric Parteli, University of Cologne.
On Pluto, the gravity is much lower, as well as the atmospheric pressure. “The winds needed to transport the sediments can therefore be 100 times lower,” he says.
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