Bizarre Image of Mars North Pole Looks Like Melted White Chocolate

A spacecraft has captured a fascinating image of Mars' north pole, revealing an unusual landscape that almost looks like ripples of melted white chocolate.

The image shows sand dunes, which form on the red planet in much the same way as they do on Earth, shaped in different ways by the wind.

The photo was taken by the ExoMars Trace Gas Orbiter—a spacecraft developed by the European Space Agency (ESA) and the Russian space agency Roscosmos—on May 25 using a color camera known as CaSSIS (Colour and Stereo Surface Imaging System).

There are numerous black patches dotted across the primarily cream-colored landscape. These occur due to the particular conditions in Mars' polar regions during the transition from winter to spring.

In the winter, the poles are coated in a thin layer of frozen carbon dioxide that turns directly from ice to a gas—a process known as sublimation—at the turn of spring, when it is heated by radiation from the sun.

"In the dune fields, this springtime defrosting occurs from the bottom up, trapping gas between the ice and the sand," an ESA statement read. "As the ice cracks, this gas is released violently and carries sand with it, forming the dark patches and streaks observed in this CaSSIS image."

The space agency says studying dune areas, such as the one featured in the image, can help researchers understand the movement of sediments around Mars.

To the right of the image, so-called "barchan" or "crescentic" dunes are visible. These dunes are crescent or U-shaped and contain characteristic horns or tips at each end that point against the direction that the prevailing winds are coming from.

Barchan dunes are common on both Earth and Mars, forming under strong winds that blow from one direction, according to the United States Geological Survey. They also require other conditions, such as a relatively flat landscape and a limited supply of sand.

On Earth, barchans—which can sometimes reach up to 100 feet high—often form around shrubs and large rocks, which help to create the characteristic crescent shape by acting as an anchor. The most famous barchans can be seen in deserts such as the Sahara in Africa and the Gobi in Asia.

On the left-hand side of the image, the barchan dunes can be seen joining and merging into what are known as barchanoid ridges.

Mars north pole
Dunes on the Martian north pole. ESA/Roscosmos/CaSSIS