February 25, 2016

Sizes of worlds

A Piece of the Solar System: This isn’t my usual sort of post. But lately my 6 year old kid has been into planets, and thanks to the many informative videos on YouTube, has been reciting various names and numbers […]
February 20, 2016

It’s a rock-eat-rock world

A Piece of Mars: This 738 x 415 m (0.46 x 0.26 mi) scene shows dark sand flowing down a channel bisected by a ~60 m (~200 ft) tall, thin “island”. That island, and many others around it (see the […]
February 8, 2016

The smallest dunes

A Piece of Mars: There are two small dome-shaped dunes in this frame (0.96×0.54 or 0.6×0.33 mi). If they got any larger, they’d form slip faces. Any smaller and they’d just be random drifts of windblown sand. Dunes form at […]
January 25, 2016

Remnants of erosion

A Piece of Mars: The gray area in the center of the 480×270 m (0.3×0.17 mi) area is an erosional remnant: once, more of this area was covered by the gray stuff, but some of it has eroded away (most […]
January 12, 2016

Springtime for sand dunes and polar ice

A Piece of Mars: This 480×270 m (0.3×0.17 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 […]
December 30, 2015

That which curves and that which is straight

A Piece of Mars: The long meandering lines snaking across the image (3.2×1.8 km or 2×1.1 mi across) are inverted channels. They are river deposits that once were the lowest part of the landscape (rivers always are), but then the […]
December 21, 2015

Curiosity about sand dunes (part 2/2)

Today is December 21, 2015 (northern winter and southern summer solstice on Earth). On Mars it is Ls = 84º, Mars Year 33 (about 12 sols from northern summer and southern winter solstice on Mars). It is sol 1200 of […]
December 14, 2015

Curiosity about sand dunes (part 1/2)

Sorry for the pun in the title there, but NASA asked for it by naming their rover like that. And you’ve seen it done a hundred times, so let’s grit our teeth, smile, and carry on. Anyway. So I’m more […]
November 24, 2015

Too steep for ripples

A piece of Mars: This 480×270 m (0.3×0.17 mi) area is a steep slope that plunges down to the upper left. A pile of dark sand, covered by brighter tan dust, clings to the hillside. Usually the martian wind blows […]