Whither the wind
The always-changing landscape
June 2, 2014Swirly rocks
June 18, 2014
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 toward the upper left. But that’s not the whole story, because, like on Earth, martian winds are always shifting. Recent avalanching and some ripples on the slip face show that the most recent wind blew toward the top of the frame. The dune is 267×110 m (876×361 ft). (HiRISE ESP_036393_2650, NASA/JPL/Univ. of Arizona)
2 Comments
is this even a dune? I don’t really understand it. From the shadows look more like a hole in a semilunar shape within a plateau.
You’re probably looking at it reversed in your mind, it’s a commong problem when looking at images of unfamiliar surfaces. The sun is shining from the lower right, so that the dark slope is pointed away from the sun and the bright slope is pointed toward the sun. It’s a positive relief feature. Try looking at the whole image at the HiRISE website (ESP_036393_2560) and see if that helps.