Photo of Martian dune field

Image: NASA/JPL/University of Arizona

This is my new favorite picture of Mars.

From Phil Plait:

The eternal Martian wind blows the heavy sand into dunes, and you can see the hummocks and ripples from this across the image. The sand on Mars is from basalt, which is a darkish gray color. The red comes from much smaller dust particles which settle everywhere.

But what are those weird tendril thingies?

In the Martian winter, carbon dioxide freezes out of the air (and you thought it was cold where you are). In the summer, that CO2 sublimates; that is, turns directly from a solid to a gas. When that happens the sand gets disturbed, and falls down the slopes in little channels, which spreads out when it hits the bottom.

This High Resolution Imaging Science Experiment site has more photos so can zoom in and look for Dejah Thoris.

Another dose of Martian awesome


  1. Hope we don’t find out that those are giante private parts of a multiwombed planet destroying monster. Just saying.

  2. So, those tendril thingies are standing up as three-dimensional objects made out of frozen carbon dioxide, or are they just a trick of perspective and are actually just stains of carbon dioxide on the side of the dune? I’m confused…


  3. So Mars has dust bunnies you can see from space.

    I cleaned under the bed this weekend. Killed off lots of dust bunnies.

    Hope they weren’t related.

  4. C’mon, you’re kidding us, right? That’s actually a closeup of a dish of strawberry ice cream with Oreo™ crumbles, right?

    1. Haha! Very subtle. From Arrested Development:

      Barry Zuckerkorn: Those are the pictures?
      Wayne Jarvis: They’re all over the news.
      Barry Zuckerkorn: [scrutinizes] Those are balls.
      Wayne Jarvis: What?
      Narrator: Barry was right. Tobias had inadvertently photographed himself in the bathtub while trying to figure out his new cell phone.

  5. I do not understand this at all.

    In winter the CO2 freezes in the summer it sublimates, that I get completely.

    What makes no sense is what exactly the frond like structures are?

    They are not running down the sides of the dunes they are all standing up.

    What are they? The CO2 has gone leaving what?

    They are neither the grey of the underlying basalt sand nor are they the pink/red of the finer particles.


  6. This High Resolution Imaging Science Experiment site has more photos so can zoom in and look for Dejah Thoris.

    They’ll be looking for the Dejah View, in other words?

  7. I’m just glad I’m not the only one who got a strong Georgia O’Keeffe vibe from this image…

  8. #15: I think this is a straight-on vertical view with the sunlight coming from about the 2 o’clock position.

  9. Ummm…So, as I see from the comments, I’m not the only one confused about the fronds sticking up from the dunes. What are those?

    Apparently, they’re not “sticking up”, but are leaking down the dunes? If so, I really don’t understand the perspective of this image…

  10. Of course we have here another piece of evidence that there is complex plant life on Mars and yet another crazy explanation from NASA that there isn’t. It’s getting to the point that the statements from NASA are becoming more hard to believe and speculative than simply saying “the red planet is alive.” No, these are not “tendrils of frozen carbon dioxide” or whatever. They are plants. Many other great photos of plant life on Mars can be seen across the web from official NASA sources. Asimov himself highlighted several that are well worth looking at.

  11. We’re built to rely on the direction of the sun, knowledge of existing objects, and haze to give us direction, scale and distance. Without these 3 items we’re all lost – craters can look like hills for instance.

    So you have to carefully try to look for those things you’d rely on and avoid applying an Earth-centric filter. If we saw this picture on earth we’d assume those are Fronds. Of course they’d be standing upright, that’s what things do here! But on Mars it isn’t that simple, we can’t make assumptions. Look carefully for shadows and light sources. Is that a hill or valley, you might surprise yourself when you try to map this image more carefully. Those fronds are laying flat against the ground.

    It’s crazy how much all of our built-in ‘knowledge’ fails us here. It’s a bit like Gabe in Fallen Angels, when he can’t comprehend how humans stand at 90degrees from ‘normal’.

  12. For those having trouble imagining what’s happening here, this is roughly it:

    As said before, it gets so cold that CO2 freezes out of the air. This frozen CO2 gathers in clumps on the dunes. The wind then blows more dust over and around those frozen patches of CO2. The CO2 acts as a dam holding the dust back. When it warms up in spring, the CO2 ice sublimates (changes from solid ice to gas without ever really entering the liquid phase) and evaporates. Suddenly you have a mound of Mars dust that used to be held up by CO2 ice that is no longer there. So, at some point, either the dust mound falls over on its own, or gets blown over by wind.

    Now, if you look closely at the image, you can see that the dark tendrils are flowing over areas of still extant CO2 ice patches. The CO2 has evaporated in channels (my guess is probably due to wind patterns flowing over the dune, more airflow over a particular section of ice means that ice melts faster), so, the dust flows through those channels as it rolls down the side of the dune.

  13. “Now, if you look closely at the image, you can see that the dark tendrils are flowing over areas of still extant CO2 ice patches.”

    But they look like they’re standing up.

  14. What looks like the TOP of a ridge out of which trees are growing up is actually the sharp BOTTOM of a white cliff which is FACING you. Picture the lines as a waterfall going almost vertically down the cliff.

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