crater
March 24, 2014
A piece of Mars: Looks like a millipede, doesn’t it? It’s something much larger and much less poisonous. It’s an ancient dune (or maybe a ripple) on Mars, that once stretched ~285 m (935 ft) from lower left to middle […]
January 27, 2014
A piece of Mars: Here are two craters, each of which is ~240 m across. On the right is an old, very eroded crater. It has old, eroded ripples on its floor. The crater on the left is younger, with […]
January 24, 2014
A piece of Mars: On Oct. 15, 2013, Curiosity drove past a crater that has small dunes or ripples on its floor. In a new HiRISE image, you can see Curiosity’s tracks from that day (its 424th sol on Mars). […]
December 23, 2013
A piece of Mars: Normally I post color images, but this one is just too cool to skip. These ripples formed ages ago: long enough ago that the impact of several small bolides formed craters (seen on the left), disrupting […]
December 11, 2013
A piece of Mars: Sand that moves into holes in the ground tends to get stuck there. That’s why this round hole ~150 m across, which was probably once a crater, is now brimming with sand and capped by ripples. […]
November 18, 2013
A piece of Mars: Is it a comet? With Comet ISON in the news these days it’s hard to tell. No, this is a brand-new meteorite impact on the surface of Mars. The impactor hit the ground, blasted through a […]
October 11, 2013
A piece of Mars: This is what the relentless work of the wind can do. That vaguely circular structure in the center of the image is probably the remains of a ~150 m diameter impact crater. Since it formed, it’s […]
June 5, 2013
A piece of Mars: Here in the bottom of a crater in Coprates Chasma is the intersection of two sets of ripples: dark, dust-free ripples at the bottom of the crater, and lighter ripples formed from debris that has come […]
January 21, 2013
A piece of Mars: What are those dark, flat circles and why are there little dunes sitting on top of them? They’re probably old impact craters that got filled in with dark sediment, and were then eroded flat. So you’re […]