June 1, 2015

Small dunes on Mars

A piece of Mars: These dunes are some of the smallest on Mars. The smallest in this frame is ~150 m long (492 ft). But the smallest Earth dunes are ~20 m across. Why are they so much bigger on […]
May 25, 2015

The looming dune

A piece of Mars: this 0.96×0.54 km (0.6×0.33 mi) scene shows a large, rippled dune that is slowly marching towards the upper right. The smooth striped band running from upper left to lower right is the slip face, where sand […]
April 29, 2015

Wind stripes

A piece of Mars: Yes, I post a lot of pictures of martian dunes with striped patterns. They’re all distinct and beautiful. So here’s another one, 480×270 m (0.3×0.17 mi) in size. These beasts moved from right to left across […]
March 18, 2015

Melty dunes

A Piece of Mars: With all due apologies to followers of the show Coupling, I have to call these things “melty dunes”. This link shows what a crisp dune should look like. The dunes in this 600×450 m (0.37×0.28 mi) […]
March 9, 2015


A piece of Mars: Ripples form endless chevrons in this 600×450 m (0.37×0.30 mi) scene. It’s really the crest of a dune that connects all the vertices in the chevrons, making that straight line that runs nearly vertical through the […]
February 17, 2015

The bright barchan

A piece of Mars: Most dunes on Mars are dark, like these and these. So why is this one bright? It’s adjacent to a more typical, dark dune. It’s possible that there are two populations of sand here that are […]
February 9, 2015

Sometimes I just have no idea

A piece of Mars: The smooth areas are eroded dunes, separated by fields of boulders (the scene is 1.51×1.14 km or 0.93×0.71 mi). The largest boulder near the center is 7.5 m (25 ft) across, the size of a small […]
January 5, 2015

The long, low dune

A piece of Mars: A long, low dune covered in long, linear ripples stretches across the scene (600×450 m; 1969×1476 ft). Dark gray areas on the dune show where sand has most recently moved. A small slip face has formed […]
December 8, 2014

Aeolian shoreline

A piece of Mars: On the left is a steep slope leading to a hill. On the right are waves – but not waves of water or any other kind of liquid. These are dunes or very large ripples, blown […]