dunes

October 25, 2013

Are you being oblique?

A piece of Mars: Barchan, or crescent dunes, are generally thought to form from winds blowing from a single direction. Reality isn’t usually that nice. Here are two barchans with crescent-shaped slip faces on their eastern (right) sides, indicating that […]
September 30, 2013

Waiting for spring

A piece of Mars: These sharp-tipped hills are dunes near the north pole of Mars. At the height of summer they’re lovely dark dunes, but because it’s just barely spring here they’re still covered in white frost (mostly CO2 ice, […]
September 4, 2013

Martian sports

A piece of Mars: In the center are two dark dunes, racing one another to jump over hurdles formed of older, now inactive dunes (or maybe those bright things are ripples, we still don’t know for sure). The dune in […]
August 21, 2013

Natural modern art on Mars

A piece of Mars: Abstract modern art? No, these are north polar dunes almost completely covered in winter frost (mostly CO2 ice). It’s early spring in this image, and the dark sand underneath the ice is only just beginning to […]
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 […]
May 21, 2013

New dust devils swirls

A piece of Mars: Swirly loops form on the martian surface as dust devils pass by, cleaning up dust on the surface and revealing the dark, rippled dune beneath. Every year the swirls get cleaned off and reform — such […]
April 16, 2013

Modern art or windy Mars?

A piece of Mars: Is it modern art? Well maybe it looks like it from a distance. Up close, this is reality on Mars. These are dark dunes in the southern hemisphere, awaking from a long hibernation beneath bright winter […]
March 22, 2013

Dunes in the spring

A piece of Mars: Dunes near the north and south poles get cold in the winter, just like they do on Earth. Except on Mars instead of H2O ice, it’s a mix of CO2 and H2O ice (mostly CO2). In […]
March 19, 2013

Nili Patera

A piece of Mars: Nili Patera on Mars is an ancient volcano. Some of the old volcanic material has been blown into rather striking sand dunes. It is the first place where dunes were conclusively identified as actively moving. Here’s […]