Tag Archives: polar

Shades and textures

A Piece of Mars: This 480x270 m (0.3x0.17 mi) scene shows the contact between two very different terrains. On the left is a bright surface with polygonal cracks (characteristic of periglacial terrain - this is at a high latitude). On ...

Eroded dune

A Piece of Mars: Barchan dunes on Mars have a characteristic crescent shape, with a steep slope ("slip face") on the inside of the sharpest curve (see examples like this, this, these, or this). This image (873x491 m, or 0.54x0.31 ...

Springtime for sand dunes and polar ice

A Piece of Mars: This 480x270 m (0.3x0.17 mi) scene shows a dark dune peeking out from under its cover of winter frost. In this picture it's late spring, but still cold up at this latitude - it's as far ...

Dune trails

A Piece of Mars: The dark dunes in this 0.96x0.54 km (0.60x0.34 mi) scene are slowly migrating towards the lower left. Look closer and you'll see brighter ripples between the dunes - the biggest ones are ~8m (26 ft) apart. ...

Frosty dunes

A piece of Mars: In this image (0.96x0.54 km or 0.6x0.33 mi), it's late winter and the sun is barely above the horizon here near the north pole. The dunes are covered in winter frost, most of which is CO2 ...

Melty dunes

A Piece of Mars: With all due apologies to followers of the show Coupling, I have to call these things "melty dunes". This link shows what a crisp dune should look like. The dunes in this 600x450 m (0.37x0.28 mi) ...

The bright barchan

A piece of Mars: Most dunes on Mars are dark, like these and these. So why is this one bright? It's adjacent to a more typical, dark dune. It's possible that there are two populations of sand here that are ...

Rivers of freezing gas

A piece of Mars: This 600x450 m (1969x1476 ft) polar scene shows sinuous channels 2-8 m (7-26 ft) wide carved out of ice-filled and ice-covered terrain. They're not formed by flowing water, but instead by flowing gas that gets trapped ...

Lumpy bumpy dunes

A piece of Mars: These funny shaped dunes were formed by winds blowing from two directions - one from the top of the frame and one from the upper right. Both winds make steep slopes (slip faces) on the downwind ...

Whither the wind

A piece of Mars: Which way did the wind blow here? You can tell by looking at the dune and its ripples. The slip face (the avalanching slope of the dune) faces downwind, so the strongest wind here mainly blows ...