This image, taken by ESA’s Mars Express, shows a dust storm moving along the ice cap at the North Pole of Mars. The Visual Monitoring Camera tracked this storm on 29 May 2019, in martian springtime. It dissipated and re-appeared with different structures over a period of days.
The brightly coloured, reflective region of the ice cap can be seen in the centre of the images. The brown swirling storm, moving at a speed of approximately 70 km/h, is on the right of the image.
The polar cap consists of water ice, onto which a layer of carbon dioxide ice is deposited in the winter. The water ice persists throughout the seasons, while in springtime the top layers of carbon dioxide ice sublimate and re-enter the atmosphere as a gas.