Dust Devils near Spirit on Sol 468

Caption NASA originale:"This picture shows a large, distant Dust Devil as a dark shape on the horizon near the right side of the image. This Dust Devil was about 5 Km (approx. 3 miles) away from NASA's Mars Exploration Rover Spirit and may have been up to 200 mt in diameter.
Smaller Dust Devils closer to the Rover appear bright against the dark ground. Spirit's NavCam took these images on the Rover's 468th Sol (April 27, 2005)".