Nasa Curiosity rover: Whipping up a 'dust devil'
With no rain in Mars' current climate, dust accumulates on the planet's surface. Winds, energised by the Sun's heating of the ground, can form large and well-formed whirlwinds known as vortices. They mostly are invisible, but when a strong vortex drifts over a dusty surface, the dust is lifted into it and reveals its shape. This animation was shot over four minutes by Nasa's Curiosity rover. The "dust devil" vortex is about one-half to one km from the rover. The dust devil is about 5m wide and at least 50m tall.