NASA images show a large field of dunes on the surface of the dwarf planet apparently composed of grains of frozen methane. But how did Pluto's extremely thin atmosphere muster the wind to form the dunes?
Image: NASA/JHUAPL/SwRI
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Scientists have discovered a large swathe of desert-like dunes on Pluto composed of frozen grains of methane, a research published in the journal Science on Thursday showed.
The parallel rows of dunes, spread over roughly the size of Tokyo, were spotted on images taken by NASA's New Horizons spacecraft during its 2015 flyby.
They are located at the boundary between Pluto's heart-shaped nitrogen glacier called Sputnik Planitia and the Al Idrisi Montes mountain range made of frozen water, scientists said.
The discovery came as a surprise as scientists doubted that Pluto's extremely thin atmosphere could muster the wind to create the features common in deserts on Earth.
"Pluto, even though it's so far away from Earth and so very cold, has a riot of processes we never expected to see," Brigham Young University planetary scientist Jani Radebaugh said. "It is far more interesting than any of us dreamed, and tells us that these very distant bodies are well worth visiting."
Image: NASA/JHUAPL/SwRI
Similar yet different
Scientists likened Pluto's dunes to those in California's Death Valley and China's Taklamakan desert, but with a very different composition.
"It's a little bit lower density than sand we're used to holding on the Earth," Radebaugh said. "So it would feel lighter in your hand, but it would still be granular and would kind of flow off your hand, and your feet would kind of crunch them as you're walking along."
Pluto, which is smaller than Earth's moon, orbits roughly 3.6 billion miles (5.8 billion kilometers) away from the sun, almost 40 times farther than Earth's orbit. Its surface is marked by plains, mountains, craters and valleys.
Methane, carbon monoxide, carbon dioxide and nitrogen exist on the dwarf planet in solid state because of Pluto's absolute zero temperatures.
Pluto's gentle winds
Scientists suggest nitrogen ice coating the surface of Sputnik Planitia transformed into gas that lifted methane particles into the air, which were then deposited by Pluto's gentle winds.
The team has yet to determine the height of the dunes, but say they are at least tens of meters tall.
Dunes have been found elsewhere in solar system — on Mars, Venus, Saturn's moon, Titan, and even a comet. But Pluto's are the only ones known to be composed of methane.
"Given we have dunes on the scorching surface of Venus under a dense atmosphere, and out in the distant reaches of the solar system at minus 230 degrees Celsius (minus 382 Fahrenheit) under a thin atmosphere, yes, dunes do have a habit of cropping up in a lot of surprising places," University of Plymouth planetary scientist Matt Telfer said.
New Horizons delivers the highest resolution images yet from dwarf planet Pluto
NASA's space probe New Horizons has been traveling through the solar system for almost a decade: destination Pluto. It did a flyby of the dwarf planet in July. It's now delivered the most spectacular close-ups ever.
Image: NASA
The sharpest ever
The US space agency NASA says these may be the best images of Pluto we'll get for decades. They show a mix of mountainous and icy regions, with craters. "These new images give us a breathtaking, super-high resolution window into Pluto's geology," says New Horizons principle investigator, Alan Stern.
Image: Reuters/NASA/JHUAPL/SwRI
And the closest ever
NASA says it used an unusual technique to capture the images. The telescope LORRI - "Long Range Reconnaissance Imager" - took pictures every three seconds. Another camera simultaneously scanned Pluto's surface. And that's how they achieved faster shutter speeds.
Image: picture-alliance/dpa/Nasa/Jhuapl/Swri
Our first glimpse of Pluto
This was one of the first images of Pluto - taken by NASA's New Horizons spacecraft and released back in July 2015. In the days that followed, we were promised sharper images as the unmanned probe got closer and closer to the dwarf planet.
Image: picture-alliance/dpa/NASA/JHUAPL
Just a stone's throw away
The big day was July 14 - and long awaited by NASA researchers. New Horizons passed by Pluto from a distance of 12,000 kilometers, which seems far away. But let's compare: the distance from our moon to Earth is thirty times as far, so 12,000 kilometers is pretty close! Here Pluto is shown with its largest moon Charon in the background.
Image: JHUAPL/SwRI
The planet that wasn't to be
Seven months after New Horizons launched, the International Astronomical Union (IAU) cancelled Pluto's planetary status. It is now referred to as a "dwarf planet" as its solar orbit is not sufficiently circular - it is more elliptic. It was the first time the IAU had defined what constitutes a "planet," and came because too many objects had been discovered in the solar system.
Image: picture-alliance/Bildagentur-online/Saurer
Comparison by size
The planets closest to the Sun are Mercury, Venus, Earth and Mars. Then there's the dwarf planet Ceres, followed by the giants Jupiter, Saturn, Uranus und Neptune. On the outer fringes of the solar system there are two tiny dots: Pluto and its moon Charon. New Horizons data (as at July) show Pluto's diameter to be a little larger than previously thought, at around 2,370 kilometers (1,473 miles).
Image: picture-alliance/dpa
Not all of Pluto's moons are round
Part of the plan was for New Horizons to investigate Pluto's moons and discover, for instance, the true size of Styx. It is thought to have a diameter of somewhere between eight and 28 kilometers. The probe took its first pictures of Charon, Nix and Hydra in January and February. In April, it got shots of Kerberos.
Image: NASA/ESA/A. Feild (STScI)
Wild dance in the lunar orbit
The moon Nix spins around wildly in its lunar orbit. These are not pictures taken by New Horizons, but a computer simulation by NASA scientists. What makes things complicated is that Nix not only circles in an orbit around Pluto, but is also influenced by the gravity of Charon - so the one moon is also a moon of the other.
New Horizons is equipped with three optical instruments, which can take pictures in a large variety of spectral bands. Two plasma spectrometers can analyze particles such as those emitted by the solar wind. The spacecraft also features dust sensors and radiometers.
Image: JHUAPL/SwRI
"Big" camera
This slide shows engineers installing the Long Range Reconnaissance Imager (LORRI) on New Horizons. LORRI is a digital camera that registers wavelengths of visible light: the heaviest part of the 8.6 kilogram camera is its 5.6 kilogram telescope.
Image: NASA
Best part of a decade
New Horizons was launched on January 19, 2006, from the Cape Canaveral Air Force Station in Florida, aboard an Atlas V rocket. The spacecraft immediately entered a trajectory designed to overcome the Earth's gravity and that of the sun. To do that it needed a speed of more than 16 kilometers per second - that's more than 58,000 kilometers per hour (37,000 mph), and with it a world record.
Image: NASA
Farther and farther from the sun
New Horizons' trajectory has taken it straight for the far reaches of our solar system. On its way, New Horizons has visited the asteroid 132524 APL, as well as the planet Jupiter, which the probe passed at a distance of 2.3 million kilometers. It collected data about Jupiter's atmosphere, its magnetosphere, and its moons.
