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Despite its thin atmosphere, Mars absolutely has weather, including massive dust devils that occasionally show themselves to NASA probes.

Dust devil spotted on Mars, way bigger than on Earth

Daniel Martins
Digital Reporter

Monday, April 4, 2016, 12:41 PM - Despite its thin atmosphere, Mars absolutely has weather, including massive dust devils that occasionally show themselves to NASA probes.

The latest one to be caught on camera, featured above and below, was spied by NASA's Opportunity rover as it trundled through the Meridiani Planum region.

Ray Arvidson, the rover's deputy principal investigator, told Mashable that while dust devils have been observed elsewhere on the Red Planet, they are less common in Opportunity's neighbourhood.

"This is one of the best dust devils that we have seen in Meridiani Planum," Arvidson said. "We are lucky to have captured this one in an image!"

Image: NASA/JPL-Caltech

Opportunity was one of two Rovers that landed on Mars in 2004, the most advanced of their time until Curiosity debuted in 2012.

Though Opportunity continues to trundle along, its twin, Spirit, stopped transmitting in 2010, though not before sending back its own treasure trove of data. 

Arvidson says Spirit caught comparatively more dust devils on camera during its time, the most famous appearing in a series of images taken in 2005, below.

Image: NASA/JPL-Caltech

That one was 34 m in diameter, according to Discovery News, much larger than dust devils on Earth.

Dust devils on Mars form the same way as they do on Earth, when rising warm air combines with wind sheer during the Martian summer, which can see daytime highs of 20oC. They are not tornadoes, which are attached to the bottom of convective thunderstorms, but on Mars, they can be larger than full-fledged twisters on Earth.

Their bases can span hundreds of metres, and the Mars Reconnaissance Orbiter spotted one in 2012 that was almost 20 km tall:

Image: NASA/JPL-Caltech

Note how tiny those sand dunes look by comparison. But though Martian dust devils can reach terrifying sizes, they are not the forces of destruction you would imagine.

Remember: Mars' atmosphere is thin, little more than one per cent of Earth's sea-level atmospheric pressure. An astronaut encountering a dust devil would not have a fun time, but though the dust would get pretty much everywhere and the winds would require them to hunker down, they likely wouldn't be sent flying (Though NASA says radio communications would be disrupted and the friction from the dust in the dry atmosphere would spark miniature lightning bolts)

WATCH: How accurate is Hollywood's portrayal of Mars' weather in 'The Martian'? Our science writer explains

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How Mars' winds build mile-high mounds

As weak as the winds on Mars would be, a recent study found they have been more than enough to raise dust mounds more than a kilometre in height.

Mount Sharp, for example, is almost five kilometres tall, rising up from the centre of Gale Crater, the landing site and sciencing grounds of NASA's Curiosity Rover.

Image: NASA/JPL-Caltech

How do the winds manage such a feat? Patiently. 

The new study, published in the journal Geophysical Research Letters, found that the wind speed and strength adds up over millions or billions of years to raise up these giant mounds -- no mean feat, given Mars boasts few of the other mountain-shaping natural forces found on Earth.

"On Mars there are no plate tectonics, and there’s no liquid water, so you don’t have anything to overprint that signature and over billions of years you get these mounds, which speaks to how much geomorphic change you can really instigate with just wind,” lead author Mackenzie Day told Astrobiology Magazine. "Wind could never do this on Earth because water acts so much faster, and tectonics act so much faster."

The researchers' study also pointed the way toward how and when Mars' climate change may have occurred, with the bottoms of the mounds being formed during a wetter era, and the tops shaped primarily by wind action.

BONUS: Mars the size of Earth's moon? Nope. We debunk our favourite space hoaxes, below

SOURCES: Mashable | Discovery News | NASA Science | Astrobiology Magazine

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