This image is circulating on Facebook.
All American flags placed on the moon are now white due to radiation from the sunGreat, now it looks like the French went there...
Did the US flags on the moon turn white?
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79Previous.comments established some people didn't get the joke, some people didn't like the joke, and some people still believe the meanings of words can be precisely determined by their etymology. None of this is relevant to the question and has been deleted.– Oddthinking ♦Commented Apr 25, 2018 at 21:12
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2 Answers
They are either bleached white or completely disintegrated.
This NASA website repeats some expert speculation on the topic.
For forty-odd years, the flags have been exposed to the full fury of the Moon’s environment – alternating 14 days of searing sunlight and 100° C heat with 14 days of numbing-cold -150° C darkness. But even more damaging is the intense ultraviolet (UV) radiation from the pure unfiltered sunlight on the cloth (modal) from which the Apollo flags were made. Even on Earth, the colors of a cloth flag flown in bright sunlight for many years will eventually fade and need to be replaced. So it is likely that these symbols of American achievement have been rendered blank, bleached white by the UV radiation of unfiltered sunlight on the lunar surface. Some of them may even have begun to physically disintegrate under the intense flux.
Of the three experts quoted, this one is actually the most optimistic. All three agree that the flags would be bleached white. Two of them believe that the flags then turned to ash. The meme shows a flag that is bleached white, but otherwise intact; this is almost certainly not the case. No one has actually been back to look at the flags, and our best orbital pictures don't show the flags in any detail, so we can't know for sure.
The Lunar Reconnaissance Orbiter has been orbiting the moon since 2009 taking "high resolution" images. If you look closely at some of these images, it is possible to see the shadows cast by some of the flags. This means that those flags are still standing, but doesn't give a lot of information about their condition.
answered Apr 25, 2018 at 16:17
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13So is there a material they could have been made from (ignoring weight, expense, etc.) that would have survived and kept its full color? Commented Apr 25, 2018 at 19:47
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117@Alexander Undoubtedly there is, but instead of spending money on that, "they literally sent out a secretary to the nearby Sears and bought an off-the-shelf flag and modified it." The flags did their jobs admirably. The only purpose of a more resilient flag would be to prevent snarky Facebook memes. Commented Apr 25, 2018 at 20:52
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39@ShadowWizard: Because no-one believes it wasn't photoshopped. The photoshop was obvious and part of the joke. It still has astronauts in the image, whereas the claim is is about now.– Oddthinking ♦Commented Apr 26, 2018 at 14:12
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16@Oddthinking: You, you may be overestimating the reasoning powers of meme-consumers... :-) Commented Apr 26, 2018 at 16:25
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8"The Lunar Reconnaissance Orbiter has been orbiting the moon since 2009 taking "high resolution" images. If you look closely at some of these images, it is possible to see the shadows cast by some of the flags. " - Link(s), please.– arothCommented Apr 27, 2018 at 1:22
Nobody knows what colors the flags are. Experts hypothesise that the color has faded by now due to prolonged exposure to intense UV radiation, but we have no direct or indirect evidence for that. We do have evidence that the flags of Apollo 12, Apollo 16, and Apollo 17 are still standing as inferred from shadows seen on the Lunar Reconnaissance Orbiter. https://www.hq.nasa.gov/alsj/ApolloFlags-Condition.html
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12It would be good to quote the relevant sections that support your claims, to protect against link rot. No indicrect evidence is a rather strong statement. We have evidence about the strong UV light on the moon, and we have evidence of the effect UV light has on bleaching dyes. Both of those are indirect evidence to support the hypothesis that the flags have faded.– Oddthinking ♦Commented Apr 27, 2018 at 2:32
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2That's the same link as the answer posted a day before. This answer doesn't seem to add anything that wasn't already said, except the mission numbers. Could have been a comment or edit suggestion. Commented Apr 27, 2018 at 6:53
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3I like this answer better, there is no clear answer as the other tries to make. Photooxidation does not occur without oxygen, other forms of bleaching may, same as in a LEO– danielCommented Apr 27, 2018 at 13:38
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1@daniel nice point. If it is an oxidative process (UV + O2) than we really don't know without an experiment trying to fade flags in a vacuum or oxygen free environment. Question is silly, answer is hubris and there simply isn't any way to really know without running an experiment in a hot and cold vacuum chamber bathed in UV and gathering evidence.– geoOCommented May 14, 2018 at 0:11