Mysterious Sand Dunes on Mars Form Almost Perfect Circles

Leave it to the Red Planet to serve up a bizarre desert scenario.

Earthlings have long harbored fascination with our nearest planetary neighbor. And now, it seems that Mars is home to circular sand dunes migrating slowly across its surface.

That’s what the University of Arizona’s High Resolution Imaging Experiment (HiRise) camera found last November, as part of its routine orbit aboard a NASA spacecraft.

HiRise picked up the photos from its spot onboard the space agency’s Mars Reconnaissance Orbiter (MRO). While tasked with a mission to monitor frost melt around the end of the Martian winter, the camera trolled across the curious dunes.

The dunes in low-tech zoom.


The dunes exhibit steep sides that slant southward, which might indicate wind direction, scientists at the university said in a March 2 statement. As for their shape, the researchers were stumped. Dunes are common on Mars, where the climate is dry and cold. But according to NASA, the round shapes of the sand piles in question are not.

Ice coats them seasonally, and they’re also creeping slowly away from Mars’ equator. Multiple outlets reported the camera’s data indicates the dunes are moving toward the poles at around a meter per Martian year (or 687 Earth days). It’s unclear how big the formations are.

MRO’s primary mission was to search for traces of water on Mars. Today, the spacecraft still operates as a communications link back to Earth for other Mars missions, and keeps sending images from the powerful HiRise. Recently, it sent back this odd find that looks like a bear’s face.

Sam Anderson

Sam Anderson spent his 20s as an adventure rock climber, scampering throughout the western U.S., Mexico, and Thailand to scope out prime stone and great stories. Life on the road gradually transformed into a seat behind the keyboard, where he acted as a founding writer of the AllGear Digital Newsroom and earned 1,500+ bylines in four years on topics from pro rock climbing to slingshots and scientific breakthroughs.