This photo has been bothering me for quite a while, so I decided to look into it further. It is shown in Wikipedia's Opposition Surge article, which is a fascinating topic that I'd like to avoid here if possible. Currently the article includes the first photo shown below, a sepia-toned photo of Neil Armstrong, taken by Neil Armstrong, with, apparently, opposition surge happening around the helmet area of the shadow on the lunar surface. The shadow is of course Buzz Aldrin, and Neil Armstrong is in the white spacesuit on the right side.

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A few clicks more and one can see that this image has been cropped and zoomed from the Buzz Aldrin's visor in a much larger image, shown below.

My question is about the connection of this photograph to the phenomena of opposition surge, coherent backscatter, or shadow-hiding. Is this just a randomly found example by an author of the Wikipedia article, or was the "discovery" of opposition surge in this already-famous-for-another-reason-or-two photo actually a notable thing? Are there other examples of this effect in local, human-scale lunar photos? Was it ever photographed or measured on purpose in subsequent Apollo missions?

Did Chang'e 3 look for it by photographing it's own shadow? Or, YuTu could have carried a little convex mirror and duplicated the shot!

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above: YuTu lunar rover photographed by Chang'e 3.

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above: NASA/Apollo photo AS11-40-5903 from here (larger size available there and at the bottom of this page.

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    $\begingroup$ I think they might have had better things to do than to duplicate well-known photographic effects? en.wikipedia.org/wiki/Heiligenschein $\endgroup$ Commented Feb 7, 2017 at 16:15
  • $\begingroup$ @Rikki-Tikki-Tavi It sounds like Heiligenschein is a catch-all phrase for a variety of distinctly different effects, do you have any other examples from lunar regolith (or any regolith on Earth for that matter) - just curious. Anyway, my question is about the history of this photo - was the Heiligenschein seen in the photo recognized during the Apollo era, is it a big thing, or is this really a sepia-toned red-herring? $\endgroup$
    – uhoh
    Commented Feb 7, 2017 at 16:25
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    $\begingroup$ Remember, the face plates had a layer of gold reflective material. I suspect that the 'sepia' toning you're remarking on is a result of this. It's not a post-processing effect (as the phrase 'sepia-toned' implies). $\endgroup$
    – BobT
    Commented Feb 8, 2017 at 14:46
  • $\begingroup$ @BobT of Yep, thanks! I was describing the process of first seeing the funky little strangely-colored image by itself, then digging deeper to see what it comes from. As you can see I've included a version of the complete AS11-40-5903 in my question to make it clear where it comes from, and the colors seem to match up pretty well. $\endgroup$
    – uhoh
    Commented Feb 8, 2017 at 17:09
  • $\begingroup$ @Rikki-Tikki-Tavi it turns out that the CAS/CSNA has indeed used Yutu to reproduce the shadow-hiding effect, and I don' think that it can be called Heiligenschein unless one proposed that there is dew (droplets of water) on the Moon. This is shadow-hiding, the main cause of opposition surge. I think that the Heiligenschein effect is the same reason that they put glass beads in adhesive tape and clothing to make it more reflective to vehicles with headlights: commons.wikimedia.org/wiki/File:BikeShoeReflectors.jpg $\endgroup$
    – uhoh
    Commented Nov 11, 2020 at 9:28

1 Answer 1


note: This is a partial answer, I'm still hoping for an Apollo-era historian (er... a historian of the Apollo-era) to answer the main question.

It turns out that YuTu DID take a photograph of the peculiar backscattering effect from lunar regolith!

In the Planetary Society's Senior Editor and Planetary Evangelist Emily Lakdawalla's article Fun with a new data set: Chang'e 3 lander and Yutu rover camera data there are several photos from Chang'e-3 and the Yutu rover. In one of them, a halo is seen around the camera's own self-photographed shadow. The caption attributes this to shadow-hiding which is a much more plausible and simple phenomenon than coherent backscattering. Open the image in a new window to view full size.

Yutu Self-Portrait in Shadow

Yutu took this photo of its own shadow on January 12, 2014. A halo appears around the right side of the rover's head because in that area, with the Sun precisely behind the right-eye camera, there are no visible shadows.

below: Chinese Academy of Sciences / China National Space Administration / The Science and Application Center for Moon and Deep Space Exploration

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below: view of Yutu from Chang'e-3 lander

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