Polka Dots on Mars: NASA Spots Amazing Circles of Sand

This story is part of Welcome to Marsour series exploring the red planet.

Mars can have a sense of fashion, and it’s become a classic pattern: polka dots. NASA’s Mars Reconnaissance Orbiter spacecraft, a long-time inhabitant of the planet, captured a fascinating image of sand dunes with highly circular shapes.

MRO’s High Resolution Imaging Experiment (HiRise) camera captured some beautiful sand dunes before, including some more common ones crescent-shaped dunes. “Dunes of many shapes and sizes are common on Mars. In this example, the dunes are almost perfectly round, which is unusual,” planetary geologist Alfred McEwen wrote for the HiRise picture- of-the-day feature Thursday.

Take a closer look at those beautiful rounded Martian mountains.


Mars is a dusty, sandy, windy place, making it a perfect planet for sand dune formation. A closer look shows that these dunes are not exactly circles. “They are still quite asymmetrical, with steep slip faces at the southern ends. This indicates that the sand generally moves to the south, but the wind can change,” said McEwen.

The HiRise camera is operated out of the University of Arizona. MRO cut the dunes in late November last year. Researchers study the area to monitor changes during the cold season. This picture shows that the cold is not in the scene.

Sightings of Mars like this may seem unworldly, but they show a connection between our two planets. We have scenic dunes on Earth, too, which tells similar stories about the wind and the changing of the seasons. There is much beauty to be found on both planets.

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