Towering dust devil on Mars
This image ran as an Astronomy Picture of the Day on March 3, 2015. Isn’t it amazing? It’s a dust devil moving across the surface of the desert world Mars, late in the northern martian spring in the year 2012. Don’t be fooled by the perspective here. Martian dust devils are huge. This one stretches 12 miles (20 km) above the Martian surface. Its core measures about 140 meters (140 yards) in diameter. By contrast, earthly dust devils are only a few tens of meters high and a few meters across.
For future astronauts on Mars, dust devils will be a hazard. They whip sand around faster than 30 meters per second (70 miles per hour), and, if you’re caught in one, visibility may drop to zero. Visiting astronauts might find their faceplates scoured by dust, as a dust devil’s high winds drive dust into every fold and wrinkle of their spacesuits.