February 13, 2017

Mars’ yin-yangs

A Piece of Mars: Is this 480×270 m (0.3×0.17 mi) scene showing a 150 m (492 ft) wide yin-yang symbol on Mars? Sort of, maybe, if you blur your eyes and lend me artistic license, but it’s not doing so […]
February 6, 2017

The two-faced dunes of Mars

A Piece of Mars: The focus of this 0.96×0.96 km (0.6×0.6 mi) scene is one of many two-faced dunes on Mars. The bright sunlit slope is one face, formed recently by wind blowing from the upper right. The dark shaded […]
January 30, 2017

Dunes + Craters = Mars

A Piece of Mars: How do you tell when a planetary landscape shows Mars, instead of Mercury or the Moon or Europa? The easiest way to tell is to look for both craters and dunes, like what’s shown here in […]
January 23, 2017

Mars’ giant sweaters

A Piece of Mars: Sometimes in the floors of small craters, the wind blows in from several directions to produce odd polygon-shaped dunes that look like crochet (maybe Mars is making sweaters for its craters – it is, after all, […]
January 16, 2017

Dunes carving up rock (3D)

A Piece of Mars: Get out your 3D blue/red glasses (or look here for a 2D version if you can’t find them). This is a 3.2×1.8 km (2×1.13 mi) scene showing dark dunes carving lanes 50-70 m (165-230 ft) deep […]
January 12, 2017

Tortoise and hare

A Piece of Mars: There’s a lot of evidence for both fast and slow movement in this 480×270 m (0.3×0.17 mi) scene. The tortoise: The rippled surface at the top is high ground: the top of a dune. Wind pushes […]
January 3, 2017

Crater ejecta on old ripples

A Piece of Mars: Mars rarely does anything without drama. Long ago in this 0.96×0.54 km (0.6×0.34 mi) scene, large ripples formed and then, presumably, lithified (turned into rock). Some time after that, an impact formed the crater in the […]
December 26, 2016

Steno’s principles, or “how to make sense of pretty landscapes”

A Piece of Mars: Nicholas Steno was a 19th century geologist, who came up with some principles that are still used today to guide interpretation of exposed sedimentary rocks. The principles seem a bit obvious, but then some of the […]
December 19, 2016

The trail of a dune

A Piece of Mars: A low, broad dune occupies the center of this 800×450 m (0.5×0.28 mi) scene, blown by a dominant wind towards the lower left. The slip face on the lee side has several small avalanches, formed as […]