Dunes on Pluto made of tiny frozen grains of methane

A high-resolution color-enhanced image of Pluto

A high-resolution color-enhanced image of Pluto

This is a significant discovery, because dunes are only produced when specific conditions occur, and recognition of these conditions on Pluto suggests that the minor planet might be much more active than previously envisaged. The dwarf planet hangs out at the far reaches of the Solar System and it's an incredibly chilly place to be. Pluto is the most remote from the Sun body in our planetary system, but is rather a "Outpost" on the way to an unexplored region of the Kuiper belt. Such winds are generated by the downward flow of gases from the tops of the surrounding mountains, as well as through the process of sublimation of methane ice, i.e. its transition from the solid to the gaseous state.

Combining an analysis of wind streak and dune-like features with spectral and numerical modeling, the scientists determined what might be the underlying architect of dunes on Pluto. They noticed a complex of ridges within Sputnik Planitia, a 620-mile-wide (1,000 kilometers) nitrogen-ice plain that forms the left lobe of Pluto's famous "heart".

It was not until 1994, when the Hubble Space Telescope took the first direct images of Pluto that any compositional variation across the planet could be seen - and even then the question of what it was made up of was not resolved.

Dunes have been detected elsewhere in the solar system including planets Mars and Venus, Saturn's moon Titan and Neptune's moon Triton, University of Cologne physicist and geoscientist Eric Parteli said.

While the mysterious dunes on Pluto may look like sand dunes, they are really formed out of tiny particles of methane. Pluto has many such similarities with Earth in its landscape, dunes and more, all though it is far away from the Sun.

BYU Professor Jani Radebaugh and a team of worldwide scientists discovered a series of "sand dunes" made of methane ice on Pluto.

Mild winds blow across the Pluto's surface at a speed of about nineteen to twenty-five miles which corresponds to approximately thirty to forty kilometers per hour.

The dunes have reportedly formed in the last 500,000 years.

Wind could create the dunes out of fine particles once they're airborne.

"The considerably lower gravity of Pluto, and the extremely low atmospheric pressure, means the winds needed to maintain sediment transport can be a hundred times lower", he said. The temperature gradients in the granular ice layer, caused by solar radiation, also play an important role in the onset of the saltation process [movement of particles over an uneven surface].

To be able to form, dunes need an atmosphere dense enough to make wind transport possible, a supply of dry particles, and a mechanism that lifts particles off the ground.

"It turns out that even though there is so little atmosphere, and the surface temperature is around -230 Celsius (-382 Fahrenheit), we still get dunes forming".

The new discovery "shows us that Pluto's atmosphere and surface are interacting in a way that geologically/geomorphologically alters the surface", said study lead author Matt Telfer, a lecturer in physical geography at the University of Plymouth in England.

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