Cosmic Diary by Lori Fenton

Subscribe to Cosmic Diary by Lori Fenton feed
Part of the Cosmic Diary Network
Updated: 52 min ago

Textured gullies

November 17, 2014

A piece of Mars. These are gullies on a martian hillside (upslope is to the upper right). Water may be what forms the channels, carrying soil and rocks downslope. The textured pattern of the lower slope is caused by the wind forming ripples on loose sediment that has been transported partway down the hill. (HiRISE ESP_038389_1105, NASA/JPL/Univ. of Arizona)

Rivers of freezing gas

November 07, 2014

A piece of Mars: This 600×450 m (1969×1476 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 under thick winter ice. The pressure of the underground gas builds until it explodes, forcing its way out, and carrying brown soil with it. Local winds blow the soil downwind (to the upper right), forming distinctive streaks. This happens every year on Mars. Awesome. (HiRISE ESP_038399_0945, NASA/JPL/Univ. of Arizona)

A way through

October 27, 2014

A piece of Mars: Wind ha blown the dark, rippled sand between jagged hills, from top to bottom in this frame (663 m or 2175 ft across). Regardless of the terrain, sand finds a way to get through — just like at the beach, it manages to get everywhere. (HiRISE ESP_037494_1685, NASA/JPL/Univ. of Arizona)

Huge wind-made cliffs

October 15, 2014

A piece of Mars: Topography in color is draped over an image of a windblown cliff. The entire shape of the landscape here was formed by wind, from the large 400 m (1312 ft) tall zigzag cliff, to the small streamlined shapes in the valley. Even the deep gorge that looks like a stream channel was formed by winds, all blowing toward the upper left. (HiRISE PSP_006694_1895 NASA/JPL/Univ. of Arizona, HRSC ESA/DLR/FU Berlin)

Mars is watching you…

October 13, 2014

A piece of Mars: This looks like a pair of eyes looking at us. It’s really some small brown hills, two of which (the “eyes”) are surrounded by dark gray sand that has blown into scours as the wind interacts with the topography of the hills. It’s a great way to tell what direction the strongest winds blow here: from the bottom to the top of the frame (the frame is 509×382 m or 1670×1253 ft). (HiRISE ESP_037995_1755, NASA/JPL/Univ. of Arizona)

Almost a dune

October 06, 2014

A Piece of Mars: This field of 2 m wide sand ripples has a dark splotch in the middle (the scene is 300×225 m or 984×738 ft). The splotch is the peak of a low hill that straddles the classification gap between proper dunes and simple drifts of sand. Maybe it was a dune that has been modified down to this bump, or maybe it’s a drift that could grow into a dune, if enough sand blew in and accumulated on it. (HiRISE ESP_038117_1385, NASA/JPL/Univ. of Arizona).

Lumpy bumpy dunes

September 30, 2014

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 (lee) sides of the dunes. With enough sand supply, the “point” between the slip faces will continue to extend toward the lower left as the two winds take turns driving the sand back and forth. (HiRISE ESP_037203_2555, NASA/JPL/Univ. of Arizona)

Changing winds

September 22, 2014

A piece of Mars: There are two sets of ripples here: tan ones and gray ones, each oriented to a different wind (scene is 300×225 m, or 984×738 ft). The gray ones sit on top of the tan ones, so the gray ones are younger. Now come the fun questions: why the different colors? Are they made out of different material (and if so, why), or are the older tan ones different because the gray sediment has weathered to tan over time? (HiRISE PSP_002387_1985, NASA/JPL/Univ. of Arizona)

Missing bedrock

September 15, 2014

A piece of Mars: Wind flow on Mars can be quite dramatic. Here, a single wind-sculpted hill stands 1.5 km (0.93 mi) wide and 600 m (1970 ft) high (color shows elevation). That sounds big, but vastly larger is the volume of material that has been removed to form it. A sandy ridge forming a “bow shock” indicates present-day winds still blow in the same direction. (HiRISE ESP_017173_1715, NASA/JPL/Univ. of Arizona)

Martian waves

September 08, 2014

A piece of Mars: The swirly candy stripes in these big dark dunes are layers inside that have been made visible by wind erosion (the scene is 1.5×0.9 km, or 0.93×0.56 mi). It’s rare to see the inside structure of dunes like this, but these are being eroded by wind blowing from the upper right. For similar examples on Earth, check out The Wave. (HiRISE ESP_037200_1765, NASA/JPL/Univ. of Arizona)

Holes around rocks

September 03, 2014

A piece of Mars: This scene (509×382 m, or 1670×1253 ft), aside from showing some lovely rippled dunes, has many car-sized boulders in it. Some are surrounded by ditches in the sand, like little moats. Why? The sand is blown away from the ground as wind impacts the rocks. My colleague Mark Bishop has studied these in more detail (read more here) (HiRISE ESP_037201_2450, NASA/JPL/Univ. of Arizona)

Which wind came first?

August 25, 2014

A piece of Mars: This scene (3.9×2.5 km or 2.4×1.6 mi) shows a surface carved by two different winds: one blowing from the right and one blowing from the bottom right. They’ve formed overlapping sets of streamlined rocks called yardangs. Can you tell which set of yardangs was formed first? It’s a little more complicated than it may first appear. (HiRISE ESP_037156_1800 NASA/JPL/Univ. of Arizona)

How the wind turns

August 18, 2014

A piece of Mars: The two shadowed hills in the upper part of this frame (497×373 m or 1631×1224 ft across) rest on a flat plain covered in large ripples. On the plain the ripples are aligned north-south, formed perpendicular to a wind blowing from the east (right). But those hills block the wind and turn it, so that the ripples between the hills change direction. This is how windblown landforms can be used as wind vanes in remote places (like on Mars). (HiRISE ESP_037188_1835, NASA/JPL/Univ. of Arizona)

Wind within vs. wind without

August 14, 2014

A piece of Mars: Dunes outside the crater are straight but the ones inside the crater look like a spiderweb. Why? This image shows just how much the topography of a crater wall can affect the wind, which produces a much more complex set of dunes inside than out on the plains. (HiRISE ESP_037195_1625 NASA/JPL/Univ. of Arizona)

What on Mars?

August 05, 2014

A piece of Mars: What on Mars is this (the scene is 600×450 m, or 0.37×0.28 mi)? It can be hard to tell. The lines are ridges of windblown dunes or ripples, the dark gray stuff is active sand blowing between the dunes, and the underlying bedrock is pale tan. But if your eyes can’t make sense of it all, just sit back and enjoy the pretty patterns of Mars. (HiRISE ESP_037161_1785, NASA/JPL/Univ. of Arizona)