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 the lower left: here the wind has disturbed those long streamers, reshaping the surface into

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 to look blue, but it’s really more of a grayish color). These don’t look like

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 the wind again, they will one day be completely buried by sediment eroded from this

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 more blue than it really is — it’s really more of a dark gray.) (ESP_030932_1750,

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 down the rim of the crater. (HiRISE ESP_030927_1675, NASA/JPL/University of Arizona)