December 6, 2012

Crescents and ripples

A piece of Mars: A lonely dune slowly makes its way (towards the upper right) across a plain. Well, look closer, it’s not all that lonely. Surrounding it on the plain are smaller streaks that are ripples, which also once […]
November 25, 2012

And the wind blew on

A piece of Mars: Small dunes (or possibly ripples) are likely no longer moving in today’s winds. Or are they? Dark splotches on their upper (northern) sides suggest some kind of wind scour has recently occurred. Winds blow, create dunes, […]
November 20, 2012

Generations of wind-blown landscapes

A piece of Mars: Some places on Mars highlight just how effective the wind is at sculpting the surface. This is a good example. Dark and light stripes on the right show not one but two successive influxes of sand: […]
November 12, 2012

Big dunes and little dunes

A Piece of Mars: A large dune (on the right, bluish) rests on a surface covered in much smaller dunes or ripples (on the left, cream). This is part of my favorite dune field on Mars. Can you spot the […]
November 1, 2012

Wind shadow, wind shadow

A piece of Mars: When the wind blows sand up against obstacles like this bright little hill, the sand is swept around to the sides. This leaves a wind shadow in the wake of the hill. It’s one of the […]
October 9, 2012

A mighty wind

A piece of Mars: I just adore that the wind can do this to a landscape. Over a long period of time, two different winds have scratched deep grooves in a rocky surface. Wind-carved rocks like this are called “yardangs”. […]
October 4, 2012

Oh, gravity, the things you can do

A piece of Mars: Steep slopes in some parts of Mars are prone to very thin landslides that leave behind dark tracks. The landslides may be triggered by the wind or nearby impacts. They always move downslope — in this […]
September 25, 2012

Winds in Gale crater, ancient and young

A piece of Gale crater, Mars: Cream-colored ripples wind their way through rough terrain. Looking more closely, the rocky surface seems to be made of highly eroded parallel ridges that are nearly perpendicular to most of the ripples. These ridges […]
September 21, 2012

Happy final voyage, Endeavour!

I rushed to work this morning, hoping to catch a glimpse of the space shuttle Endeavour on its final trip, piggybacking on another plane to its final destination as a museum dust magnet. Well, I suppose there are worse ways […]