May 27, 2012

Tuning forks of the wind.

A piece of Mars: Small, dark ripples have overridden larger, bright ones. The larger ones have some interesting shapes — arcs, splits that resemble tuning forks, and even circles. Their shape is accentuated by the smaller, very regular ripples between […]
May 24, 2012

Fashionable stripes of Mars

A piece of Mars: Is it the latest in patterns for ties, or is it Mars? (Can it be both?) These are some unusually regular dunes on Mars, separated by a bouldered surface. The dunes have interesting pale bands common […]
May 23, 2012

At the edge

A piece of Mars: Old, subdued dunes (in blue) near the south pole on Mars. This shows the edge of a dune field, with white rock-strewn surface beyond the sand. Criss-crossing the sand are the tracks that dust devils have […]
May 22, 2012

When dunes die

A piece of Mars: This is what dunes look like when they die. At least on Mars. On Earth they typically get buried or eroded away. On Mars geology works slowly enough that the steep slopes of dunes are gradually […]
May 21, 2012

Staircases

A piece of Mars: Sedimentary layers on Mars are revealed by sandblasting. These are giant staircases dropping down towards the upper right, looking like some old eroded temple or city. Some bluish sand remains as a reminder of what scoured […]
May 20, 2012

Ripples in a crater

A piece of Mars: Many small craters on Mars are filled, at least in part, by small dunes or ripples. It’s one of the distinguishing features of Mars — a surface marked by geology both old (craters) and young (dunes). […]
May 17, 2012

Dust and oddities

A piece of Mars: In the dustier regions of Mars, there are many small dark streaks on steep slopes that we don’t understand well. Because we don’t know much about them we call them “slope streaks”, which is not the […]
May 16, 2012

Wind and hills

A piece of Mars: Blueish and yellowish ripples wind their way around a bright hill. The yellowish ones are probably not moving anymore, but the blueish ones are likely still active from time to time. (HiRISE ESP_020889_1320)
May 14, 2012

Swirls like ribbon ice cream

A piece of Mars: When the wind erodes layered rocks, it can create a dramatic swirly pattern like this. It looks like ribbon ice cream to me. Mmm, rocks. (HiRISE ESP_011582_1730)