Frosty blue dunes on Mars

By Phil Plait | February 27, 2012 7:00 am

It’s been a while since I’ve posted a jaw-dropping high-res picture from Mars, so how about this one: a gorgeous shot of frost coating dunes on the surface of the Red Planet?

[Oh yes, you want to click that to enaresenate.]

This picture was taken by the HiRISE camera on board the Mars Reconnaissance Orbiter, which takes extremely detailed images of the surface of the planet. It shows wind-driven sand dunes on Mars, rippling in a similar way as on Earth. The sunlight is coming from the upper left direction, and where the light hits the surface you can see the familiar reddish cast; that’s actually from very fine-grain dust laden with iron oxide — rust!

But the shadows, where the Sun doesn’t reach, it’s cold enough that carbon dioxide in the Martian air freezes out, forming a thin layer of dry ice on the surface. In this image — where the colors have been enhanced so you can see the effects better — this shades the dunes blue. You can see the frost not just covering the dunes in general, but hiding in the troughs of the ripples too (which I think is why the sunward facing parts of the dunes can look blue; that’s from the ripple shadows). The non-color-enhanced version showing the entire dune region can be found here — and is stunning in its own right.

These dunes fascinate me. The sand on Mars is actually basaltic, making it look grey to the eye. Those grains are big enough that they don’t move as easily as the finer dust, and they pile up to form the big dunes, with the redder dust coating them. The color can change when frost forms, as in the picture above, but you also get incredibly dramatic and simply stunning patterns when dust devils — tornado-like vortices that form when wind blows over warm air rising off the surface — lift up the red dust and expose the grey basalt underneath. The swirling patterns are intricate and incredible, as you can see in this picture here (click to embiggen and get more details).

Pictures like this remind me viscerally that these objects we see in the sky are not just some distant lights, they are whole worlds. They have fantastic details and are as diverse and have complex interactive systems as any we find on Earth. This makes their study important, fascinating… and of course, astonishingly beautiful.

Image credit: NASA/JPL/University of Arizona. Tip o’ the heat shield to HiRISE on Twitter.


Related posts:

The artwork of the Martian landscape
Martian dunes under the microscope
The Devil is in the details
Happy first day of spring… Mars!

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (27)

  1. True_Q

    10 on the scale of awesomeness

  2. Chris

    That second one looks like it would make a good tattoo.

  3. Nigel Depledge

    Enaresenate?

    What has this to do with compounds of arsenic?

    (Yes, I know that it’s spelt arsenate not aresenate, but that was too good a straight line to let go.)

  4. Martin AA6E

    What a fine desktop background image!

  5. Brett

    Both of those pictures are life-altering. My head literally swims from looking at the full page images and “Across the Universe” plays inside. Thanks so much for your site.

  6. Wzrd1

    Those aren’t dust devil tracks in the second picture, they’re crop circles. ;)
    Nigel Depledge, I was thinking encyanate. :D

  7. Andy B

    Interesting and awesome as always!

  8. JellySock

    Wow… is that a sort of interference pattern to be seen on the center dune? Phil, this is so beautiful. Thank you for all you do.

  9. With all that sand likely building up static, any astronauts visiting could end up charged with basalt…..

  10. Todd

    My new desktop background. Many thanks!

  11. Matt

    Clearly Mars believes that acid-washed denim will be making a comeback this spring fashion season.

  12. Wzrd1

    To be serious though, I DO remember reading about one of the rover designers, who was concerned about possible electrostatic discharges from the Martian dust devils. There was no documentation at the time about electrostatics with Terrestrial dust devils, so he went into the desert with some instruments and documented thoroughly.
    A lot of people who initially had disparaged the notion were shocked, so the rovers received extra protection against ESD and were shut down in the early mission when dust devils came their way.
    I don’t know if they still shut down Opportunity when dust devils are heading its way.

  13. Cynthia

    The picture is beautiful. I love the dunes and the blue ripples. The ripples make me want to go swimming.

  14. Alison Moodie

    Embiggen! I love it. 8-}

  15. Alison

    Embiggen: I love it! 8-}

  16. Alison

    Embiggen! I love it. 8-}

  17. Where are the expert comments from Richard C Hoagland ?

  18. Darokthar

    What is that artefact on the lower left? In the shadow in the left corner? It looks like an termite hill with tentacles? Maybe there are mites on mars, which ate all the plants?

  19. Gary Ansorge

    Umm, body paint,,,

    ,,,or tattoos. Either is good for me,,,

    Great pics,,,

    Gary 7

  20. kat wagner

    A new quilt top – that’s what the first photo looked like to me without thinking about it. So I’m glad to know Mars looks beautiful in blue. O my gosh.

  21. Great image – although it could almost easily be a photo from above the Sahara, Namib or Great Sandy Deserts here on Earth as much as Mars. :-)

    Where are those tell-tale martian canals craters? ;-)

    Pictures like this remind me viscerally that these objects we see in the sky are not just some distant lights, they are whole worlds. They have fantastic details and are as diverse and have complex interactive systems as any we find on Earth. This makes their study important, fascinating… and of course, astonishingly beautiful.

    Quoted for truth – very well said and seconded by me. :-)

  22. Nigel Depledge

    Wzrd1 (6) said:

    Nigel Depledge, I was thinking encyanate

    Heh. So were you thinking of the colour or the cyanate anion?

  23. MarkW

    Enaresenate? I thought it was enbarsoomenate for Mars?

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