August 8, 2013

Different day, different sand

A piece of Mars: Creamy dunes (or maybe they’re very large ripples) wind their way northward between mesas. More recently darker, more mobile sand (bluish here) has piled up against the western slopes of the mesas. We don’t know why […]
July 29, 2013

Screaming winds

A piece of Mars: This image is way up high on the Tharsis Montes on Mars, at an elevation of 5900 m (19,350 ft). At night the wind comes screaming down from some of the tallest mountains in the Solar […]
July 8, 2013

South polar dunes

A piece of Mars: The blue structures are rippled dunes found not far from the south polar cap of Mars. They are probably partially active, enough to create the fine ripples found on and between the dunes. But the steeper […]
July 3, 2013

Topography

A piece of Mars: Topography makes for great landscapes. It also funnels winds, forcing dunes and ripples along particular pathways. Here a cliff (high ground is yellow) has forced low-lying, dark ripples to migrate up a slope at the end […]
June 26, 2013

Pale gold satin sand

A piece of Mars: Sand sometimes piles up on steep slopes. It forms downslope streaks as it slides downhill, which here appear like long narrow stripes, like shimmering satin (down is toward the lower left). Note the wind-blown ripples in […]
June 21, 2013

Polygons of dunes

A piece of Mars: Yep, these are dunes shaped into polygons. Each “cell” is about 25 m (~80 ft) across. The crests of these things are outlined in blue, as if somebody traced them with a pen (well it’s stretched […]
June 17, 2013

Hills, boulders, and wind

A piece of Mars: In the lower left of the image, a small hill stands above a plain partly covered by stabilized ripples. Boulders have rolled down the hill as it slowly erodes. If these ripples aren’t ever activated by […]
June 7, 2013

Blue ribbon

A piece of Mars: In ancient, wind-carved hills, a bluish ribbon of actively moving sand still winds its way. It is a remnant of a long-lived period of wind scour that shaped this landscape. (And it’s been stretched to look […]
June 5, 2013

The colors of geology

A piece of Mars: Here in the bottom of a crater in Coprates Chasma is the intersection of two sets of ripples: dark, dust-free ripples at the bottom of the crater, and lighter ripples formed from debris that has come […]