Exposing PseudoAstronomy

May 10, 2013

Podcast #74: The True Color of Mars

Conspiracy strikes!
But Stuart says, “Mars’ color
Is natur’ly red.”

This episode is hopefully the last for a few months on image processing gone horribly wrong. I swear.

This one is an episode I’ve been wanting to do for awhile — at least since last year — but I had been putting off because I didn’t want to listen to Richard Hoagland again and take detailed, dense notes. And I’d covered Richard a lot recently. And I’d done a lot of image analysis episodes. The claim is that the color of Mars is fake, that it really should look like Earth. And since no space agency’s photos look that way, they’re all fake color.

The episode includes has two Coast to Coast clips (both Hoagland), Q&A, feedback, and a puzzler! The episode is around 40 minutes long.



  1. Cripes, you’re patient. 🙂

    Comment by Bob — May 10, 2013 @ 11:37 pm | Reply

  2. Great episode. I saw a Hoagland talk before where he asserts that some part of Mars is a forest, I think, and showed some colorized green photo of a part of Mars. I think I remember something about big hole being there, too. He’s a source of constant amusement. Have you cone across what I’m referring to? I’ll see if I can find an image.

    Comment by Julian Janssen — May 11, 2013 @ 12:42 am | Reply

  3. Regarding the first Viking images of Mars:

    “The first colour photo from Lander 1 revealed a reddish brown landscape, strikingly similar to a plot of Arizona desert, with light blue sky beyond the horizon. The sky colour astonished observers until color values were rectified (by comparing them with colours painted on the lander). The revised photo showed a pink sky. It was tinted by the red dust in the atmosphere.”

    (Chapter “Mars”, p.197, The Illustrated Encyclopedia of Space Exploration, Richard S. Lewis, Salamander Books, 1983)

    Secondly, a nitpick, your description of the Viking Lander imaging system gave the implication that the landers used a system similar to the Lunar Orbiters where film was exposed and then scanned prior to transmission. The imaging system used on the landers was not dissimilar to modern CCD cameras. The details can be found in chapter 3 of “The Martian Landscape”


    Finally some Sci-Fi geekery, Hoaglands, “Humans are refugees from Mars” scenario is the one used by author H. Beam Piper for his ‘Paratime’ series of short stories. All of the alternate histories Piper created for the series have as their start point the arrival of on Earth of refugees from Mars after that planets resources have been exhausted.

    Comment by Graham — May 11, 2013 @ 4:03 am | Reply

  4. Small Adendum,

    Chapter 12 of “The Martian Landscape” covers the first images story, to quote:

    “When the first color data from Mars were received on Earth, we immediately used the same normalization techniques to calibrate the image. The result was surprising and disquieting. The entire scene, ground and atmosphere alike, was bathed in a reddish glow. Unwilling to commit ourselves publicly to this provocative display, we adjusted the parameters in the calibration program until the sky came out a neutral gray. At the same time, rocks and soil showed good contrast; the colors seemed reasonable. This was the picture released eight hours after receipt of the data. But to our chagrin the sky took on a bluish hue during reconstruction and photoreproduction. The media representatives were delighted with the Earth like colors of the scene.

    Meanwhile, continued analysis supported the reality of an orangeish tint throughout the scene, the atmospheric color resulting from small suspended soil particles. Several days after the first release, we distributed a second version, this time with the sky reddish. Predictably, newspaper headlines of “Martian sky turns from blue to red” were followed by accounts of scientific fallibility. We smiled painfully when reporters asked us if the sky would turn green in a subsequent version.”


    Comment by Graham — May 11, 2013 @ 4:07 am | Reply

  5. Excellent poddery, well done. For a too-good example of how NOT to color-balance an image, see Mike Bara’s utterly woeful attempt to justify the ‘Data’s Head’ lunar rock. His laughable Youtube demo is embedded in this blogpost, which provides an explanation of why he would want to make a fool of himself like this.


    Comment by Expat — May 11, 2013 @ 6:54 am | Reply

  6. I learned a little bit of Brazilian Portuguese while working with folks from Brazil. The best imitation to pronouncing the name I could come up with, would make it closer to “see-dah-DOWN”, with the “down” very nasalized.

    Comment by Rick K. — May 11, 2013 @ 10:42 am | Reply

    • I tried to use an online pronunciation guide this time, so I got sorta close, but Hoagie was WAY far away. How you get “see-uh-DAR-ë-ö” from Cidadão is beyond me.

      Comment by Stuart Robbins — May 11, 2013 @ 10:44 am | Reply

  7. I’ve been mentoring a local high school group that has been building and flying payloads on weather balloons. We reach about 100,000′ (30 km) before the balloon bursts. At that altitude, pressure is about 1 kPa (1% of the surface pressure) and temperature of 225K. Coincidentally these are pretty close to those on the surface of Mars (though the Martian surface temperature is quite variable).

    Our videos from that altitude, just like those from every other group that has flown cameras to that altitude, show the sky to be absolutely black. That’s just how the Martian sky would look from the surface if there wasn’t so much dust suspended in the atmosphere. That establishes the color of the Martian sky, and that’s why it closely matches the color of the surface except in special situations like a sunset when the atmospheric path is unusually long.

    Comment by Phil — May 15, 2013 @ 7:50 am | Reply

    • We have a lot of dust in Earth’s atmosphere. Why doesn’t it affect the color of ours as much as on Mars? The way I understand it, the large amount of Nitrogen molecules in Earth’s air contributes a huge effect, and I presume water contributes as well. I’ve read there’s very little water in the Martian atmosphere, so maybe that’s why dust plays such a prominent role?

      Comment by Rick K. — May 15, 2013 @ 11:22 am | Reply

      • I’m not a meteorologist or climatologist, but I think you’re right about dust and water. On earth, rain tends to wash dust out of the troposphere, but that doesn’t happen on Mars.

        Comment by Phil — May 19, 2013 @ 5:03 pm

    • Thanks for the info. I’ll bring this stuff up in the next-next episode.

      Comment by Stuart Robbins — May 17, 2013 @ 9:00 am | Reply

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