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I recently learned about Cherenkov Radiation which produces an eerie blue glow, such as when viewing a nuclear reactor submerged in water. This effect was known about as early as the 1930's. However, nearly every representation of radioactivity and radioactive materials I've seen in popular media is associated with a bright green glow. Aside from radium being used in radioluminescent paint and uranium being used as a glass colorant, I have found few if any examples of this "green glow" in real life.

What was the origin of the association between radioactivity and the color green in today's media?

A. W.
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    Hi, welcome to SF&F. Green glowing stuff being toxic/dangerous is common enough to be a trope: Sickly Green Glow (warning TVTropes). – DavidW Apr 02 '20 at 21:58
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    As for the beginnings of a possible answer, I believe that radium - one of the first radioactive materials that people might have seen - has a greenish glow. – DavidW Apr 02 '20 at 21:59
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    This article agrees with the theory that it's probably from radioluminescent paint which contained radium & phosphors. The phosphors give the green glow, pure radium itself has a slight bluish glow, due to its alpha radiation ionizing nitrogen in the air. – PM 2Ring Apr 02 '20 at 22:07
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    @PM2Ring Ah yes, that was it precisely. The glowing watches. I forgot it was radium+phosphor. – DavidW Apr 02 '20 at 22:38
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    The phosphor used in radium paint is sphalerite, aka zinc sulfide -- it glows a yellow-green color when excited by any sort of radiation. UV, alpha, beta, or it will even store energy from regular visible light and continue to glow for some time (minutes to hours). This is also what's found in most "glow in the dark" plastics and paints. – Zeiss Ikon Apr 03 '20 at 12:10
  • Related: Why are acids usually depicted in fiction as green? –  Apr 04 '20 at 09:45
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    Tritium also has a green glow – john doe Apr 05 '20 at 09:27
  • Interestingly, in The U-Ray, a comic from German-occupied Belgium composed in '43, the radioactive mineral "uradium" emits a yellow glow. (Who would trust a Captain called "Dagon"? Really!) – David Tonhofer Apr 05 '20 at 16:04

2 Answers2

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This Quora question cites three possible sources:

The rumor is that reporters seeing the first nuclear reactors at criticality did so through lead-doped glass; when you dope glass with lead, it gives it a green tint - so the reporters, not having this explained to them, thought that radiation was green.

....

These are uranium ores, which are jade green crystals:
Image of uranium ores, which are jade green crytals

These are uranium glasses, which emit bright green light under UV illumination:
Image of uranium glass emitting a bright green light under UV illumination

Lastly, as mentioned in the comment above, the radioactive material people were most likely to encounter in daily life was radium, famously used in self-illuminating paint, which glows with a green light when combined with phosphorescent copper-doped zinc sulfide.

FuzzyBoots
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    I think for completeness it would help to also mention the radium-doped phosphorescent paint as discussed in the comment linked above. – DavidW Apr 02 '20 at 22:47
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    Done. It is kind of funny how the public perception leads to such stereotypes. – FuzzyBoots Apr 02 '20 at 22:50
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    In the case of the radium paint, it's the paint that glows green rather than the radium itself. The invisible radiation from the radium excites a material in the paint. That stuff glows. – JRE Apr 03 '20 at 05:45
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    Why would someone make drinking glasses out of uranium? – DonyorM Apr 03 '20 at 12:46
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    @DonyorM: Maybe the same reason the Romans made drinking cups from lead, because they enjoyed some of the side effects. – FuzzyBoots Apr 03 '20 at 12:55
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    @Donyor I know it sounds crazy, but radiation was viewed (or at least marketed) as health-enhancing in the early 20th Century. Anyway, the glass was mostly ordinary (silica) glass with just enough uranium to produce the effect in the picture. – Spencer Apr 03 '20 at 13:25
  • @DonyorM Uranium yields a yellowish green color in glass, and an attractive bright yellow in ceramic glazes. Jack Vance used this fact in his short story, The Potters of Firsk. – Invisible Trihedron Apr 03 '20 at 14:23
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    Too much kryptonite. – Clockwork Apr 03 '20 at 16:23
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    @DonyorM, Why not? People were using uranium to color glassware and ceramic glazes since long before anybody knew that the stuff was dangerous. – Solomon Slow Apr 03 '20 at 17:34
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    The trace amounts of uranium in ore don't give off a particularly harmful amount of radiation anyway; it's mostly "depleted" uranium, which is why it needs to be processed into fuel or (especially) weapons. It's more dangerous for its toxicity, similar to lead. – Cadence Apr 03 '20 at 19:20
  • @Cadence: Not exactly. Depleted uranium is what's left after the fissionable stuff (U-235) is removed. And even the U-235 isn't particulary radioactive (half-life 704 million years vs 4.4 billion for U-238): it's fissionable, which is a different thing. – jamesqf Apr 04 '20 at 18:08
  • I would suggest another possible reason, which is that the glowing things people would have seen before radium &c, such as glowworms and foxfire (https://en.wikipedia.org/wiki/Foxfire ), tend to have a sickly greenish glow. – jamesqf Apr 04 '20 at 18:12
  • @Cadence it's perfectly possible to build a reactor that runs on natural uranium at 99.3% depletion. You just have to know what you're doing, like the designers of Hanford B, CanDU, and RBMK - all of which not only work on unenriched uranium, but are factored to allow fuel changes while underway, a rather useful feature if you want to breed plutonium. – Harper - Reinstate Monica Apr 05 '20 at 13:15
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Clearly Radium Dials which were in relatively wide circulation before people decided to die in car crashes instead (image from wikimedia, user Arma95):

enter image description here

Peter - Reinstate Monica
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    I'm a bit confused about your second comment about car crashes... – FuzzyBoots Apr 03 '20 at 12:22
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    @FuzzyBoots It is a bit of a non-sequitur, I agree. I think he's referring to the idea that radium paint was used to make dials that glow in the dark (specifically, the dials on car dashboards,) but that practice was discontinued when other - non-radioactive - means of making them glow were discovered. So, people "chose to die in car crashes" rather than "to radiation poisoning from the dials." (I don't know how realistic that threat ever was, but I can certainly see it being a hot topic back in the day.) – Steve-O Apr 03 '20 at 13:43
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    @Steve-O The dashboard dials, being behind glass, were pretty much harmless to the driver, unless you pulled it out and licked it. The only people that got radiation poisoning from those were the people whose job it was to paint them, and that was because they were wetting the brushes in their mouths. Alpha radiation (such as that found in radium paint) can do a lot of damage, but doesn't penetrate easily, so it's mostly only a problem if you directly ingest it. – Darrel Hoffman Apr 03 '20 at 14:24
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    @Steve-O The health issues from radiation (especially the risk of ingesting or inhaling Radium traces after damaging a watch or clock) were being discovered around the time automobiles took off, which do a much higher damage to public health. – Peter - Reinstate Monica Apr 03 '20 at 14:47
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    @Peter Non sequitur. The presence or absence of radium on dials did not affect the safety (or otherwise) of cars. The number of pirates fell too, but that's not a cause either. ;) You can probably look at the graphs and see car-related accidents increase around that time, sure, but that relates to a massive increase in the number of cars, as well as a significant increase in engine power without a corresponding improvement in brakes, tyres or suspension, and the 1950s approach of building large flashy cars with no structural strength which were the direct reason crash tests were started. – Graham Apr 04 '20 at 11:13
  • @Peter-ReinstateMonica there's also the phenomenon of risk homeostasis, where people "consume" a reduction in risk rather than just be safer. Most examples I've read were about cars, e.g. they make cars safer with antilock brakes, drivers drive faster so their risk of crashing remains the same. I don't know if it commonly applies to otherwise unrelated risks like radium poisoning and car crashes, but why not? – stannius Apr 04 '20 at 14:58
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    @Peter-ReinstateMonica Don't worry, some of us got the joke. – barbecue Apr 04 '20 at 16:10