Hello, long time no hear! Been fighting fires up northern NSW, Australia!
No. It depends primarily on the relative angles and the strength of illumination. You'll see the effect with whichever is the brighter. I've seen a double moon out of a double glazed window on many occasions, for example.
Yes, it depends on what is brighter, here's an example of double images through the double-paned glass of the LM.
https://www.flickr.com/photos/projectapolloarchive/21495627468/in/album-72157658638144538/. You'll notice that the image occurs on the brightly lit objects; the horizon, the Earth and the sun's rays on the thrusters, note how darker LM components on the dark background aren't readily duplicated. If you look further in the album the image is contained in you'll see LM shadow images taken through the LM windows. To begin with they seem like single shadows, then it begins to double up and move in different directions but everything else remains single. Rocks, other shadows, the flag and the horizon. In other images bright objects like ALSEPs and astronauts aren't duplicated. Finally, shadows aren't brightly lit, illuminating them destroys them.
Combat Wombat said The other curious thing here is that it's only the LM shadow and some craters that are doubled, wouldn't the horizon, the many rocks and their shadows be duplicated also?
Not necessarily. Given the relative wide angle of the camera lens I wouldn't expect the see the entire image duplicated in that way, just certain part of it depending on the relative angles of the optical axis and the window.
There are images where components of the LM shadow are duplicated but others nearby or adjacent are not. Seems like a very selective physical property and a poor quality camera to take all the way to the moon!!!!
So what do you think is more likely? That you have not fully grasped the optical effects in the imagery, or that somehow this common occurrence is proof of something dodgy and no-one picked it up before publishing the images and footage over the course of a bunch of missions covering a few years until you came along half a century later?
It's not just me questioning this, I watched the landings as kid and became a NASA fanboy. Long story short, I became aware of the archive a few years ago but it was not until earlier this year that I began to look at it, the stabilized HD DAC footage and LROC images, not impressed. Seems that many of the Apollo images were not readily available until fairly recently and there's many to view, 1000s of them. If they were all available for analysis half a century ago the story could've been quite different. I've searched for explanations, NASA's Apollo Lunar Surface Journal calls these shadows 'dramatic washout'. The moon wiki calls it the 'Heiligenschein effect'
https://the-moon.us/wiki/Retro-Reflection_phenomena. People on this forum and others call it an optical effect of the windows, lenses and lens filters but I've never seen any scientific description. I used to do silver halide photography back in the 80s, they look double lit and/or overlaid to me and were probably never meant to see the light of day. I'm surprised they weren't 'lost' like much of NASA's archives and technologies. My silver halide and 35mm camera are long gone but time permitting I'll see if I can build analogues of LM components and see what transpires under natural and artificial light(s). Till then I'll just annotate some images from the archive and attach them.
Thanks, Combat Wombat
