Slug-Like Dunes on Mars

Just in case you didn't think Mars could get any more alien, here's an intriguing photograph taken by the HiRISE camera aboard the Mars Reconnaissance Orbiter (MRO) in 2007. What are those dark objects? Giant slugs slithering over the Martian plains? Are the Sandworms from Frank Herbert's classic 1965 novel "Dune" real?

As much as I'd love to be announcing the discovery of an alien herd of rampaging giant invertebrates, alas (as you might have guessed) this is actually an image of some odd-looking dunes inside a 150 kilometer-wide Martian crater.

Uncovered by the Universe Today's ace writer Nancy Atkinson when she was browsing the latest photos from the Mars orbiter's website, these dunes are probably still active, gradually being shaped by the Martian winds to this day.

I've had a fascination with the dune features on Mars ever since the MRO first beamed these beautiful high-resolution pictures back to Earth. While the dunes often look alien and bizarre-shaped, there's a strange familiarity with the sand dunes we find on terrestrial beaches. They are, after all, shaped by the same thing: wind.

But why are the dunes in Proctor Crater so dark when the surrounding landscape appears to be scattered with brightly colored boulders and smaller dunes?

"The dark dunes are composed of basaltic sand that has collected on the bottom of the crater," remarks to Maria Banks, a geologist and planetary scientist from the University of Arizona.

It would appear that these large dunes were formed recently as they overlay the brighter rippled landscape. Basalt is formed as a product of volcanic activity, but over the eons, Mars' winds have eroded this rock into fine basaltic sand, eventually creating these dramatically contrasting sand dunes.

For more assorted Mars dunes, browse through the HiRISE database.