NASA’s Mars Reconnaissance Orbiter (MRO) has delivered incredible insights into the Red Planet, often capturing intriguing images of landscapes that don't have any earthly comparisons. As a frigid desert, Mars has its share of sandy dunes that under certain conditions create curious shapes. The latest image, captured just a few months ago, shows unusual dunes that are almost perfectly circular.

“Sand dunes of many shapes and sizes are common on Mars. In this example, the dunes are almost perfectly circular, which is unusual,” Alfred McEwen wrote in a HiRISE blog post where the panorama was presented as Image of the Day. “They are still slightly asymmetrical, with steep slip faces on the south ends. This indicates that sand generally moves to the south, but the winds may be variable.”

The image is part of a series of observations from the High-Resolution Imaging Experiment, or HiRISE. The incredible camera has been studying changes in the Northern Hemisphere of Mar as winter slowly turns into spring. The area of the polka dot dunes was in fact covered in frost, although it is no longer visible in the more recent image taken on November 22, 2022.

HiRISE has previously spotted trains of dunes moving as well as intricate sandy structures. Its camera has a resolution of 30 centimeters (10 inches) per pixel. This means we can see Martian features under a meter (40 inches) quite clearly.

However, there is plenty still to be understood about Mars and its strange dunes.