# Laser art on the Moon! **URL:** \ **Category:** Factual Questions\ **Created:** [November 8, 2007, 10:51pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725 "2007-11-08T22:51:19Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [November 8, 2007, 10:51pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/1 "2007-11-08T22:51:19Z")
I’ve kicked this idea around for some time, mentioned it here and there, but now I’d like to get down to some hard-core theorizing. Given that laser shows like the one at [Stone Mountain Park, Georgia](http://www.stonemountainpark.com/mini-section/default.aspx?id=5) can draw large images, what would it take to use the new Moon (i.e. the moon at a time when its sunlit face is pointed away from Earth) as a canvas? Given the moon’s apparent size (roughly comparable to a fingernail held at arm’s length), I wouldn’t expect readable text, but consider a corporate logo, like Pepsi’s red-and-blue, or Mercedes’ propellor, or anything else roughly circular. If the albedo of the moon is in the 10-15% range, how much energy is required to draw something visible to the naked eye, putting aside issues of light pollution from Earthbound sources? ---
**Author:** ![Argent\_Towers](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)\ **Post date:** [November 8, 2007, 11:24pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/2 "2007-11-08T23:24:16Z")
I don’t have an answer, but I have to say that the idea of a corporate logo on the moon is extremely annoying. I think I would seriously consider moving to another solar system if I had to look at the Pepsi logo on the moon even once a year. The Bat sign, though, I wouldn’t mind. ---
**Author:** ![ChrisBooth12](https://avatars.discourse-cdn.com/v4/letter/c/e95f7d/32.png) [@ChrisBooth12](https://boards.straightdope.com/u/ChrisBooth12)\ **Post date:** [November 8, 2007, 11:26pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/3 "2007-11-08T23:26:19Z")
I believe it would actually be against the law. at least by the FCC that is. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [November 8, 2007, 11:30pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/4 "2007-11-08T23:30:33Z")
> [@Bryan Ekers](#): > > what would it take to use the new Moon (i.e. the moon at a time when its sunlit face is pointed away from Earth) as a canvas? Remember that when the moon is at its new phase, it’s in almost the same direction as the sun. If the sun is still in the sky when you’re projecting your logo onto the dark near-side surface of the moon, the visual effect is probably not going to be very impressive. What you want is for your artwork to show up clearly on the moon against a **dark** sky. For that, you’re going to have to accept at least a little white crescent on the otherwise dark disk of the moon, so that it will be far enough away from the sun to be visible after sunset. (And the nearly-new moon won’t be above the horizon for very long itself, leaving you with quite a short display time which will probably piss off your corporate sponsors. Why not project something onto the bright disk of the **full** moon instead, like Batman’s Bat-signal? [ETA: Hi **Argent**!] The full moon stays up all night and there’s no direct sunlight competing with it.) ---
**Author:** ![Cabbage](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@Cabbage](https://boards.straightdope.com/u/Cabbage)\ **Post date:** [November 8, 2007, 11:33pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/5 "2007-11-08T23:33:24Z")
I definitely remember reading that Pizza Hut considered doing just this at one time. They abandoned it when it was pointed out that the logo would have to be the size of Texas in order for it to be legible from Earth. Here’s a reference to that story: > [@](#): > > …they wanted to project the chain’s updated logo onto the moon…(but)…the logo would have to be as big as Texas to be seen by earthlings without telescopes. [http://www.indianexpress.com/res/web/pIe/ie/daily/19991004/ibu04033.html](http://www.indianexpress.com/res/web/pIe/ie/daily/19991004/ibu04033.html) ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [November 8, 2007, 11:34pm UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/6 "2007-11-08T23:34:22Z")
The moon is a lot smaller in the sky than you think. It would have to cover the entire face of the moon to even be seen, let alone readable. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 9, 2007, 12:04am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/7 "2007-11-09T00:04:10Z")
As I said in [this](http://boards.straightdope.com/sdmb/showthread.php?t=321951) previous thread on the subject, I think it would be a less taxing engineering task to construct a shadow puppet the size of India, and use that to form the desired image on the moon. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 9, 2007, 12:05am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/8 "2007-11-09T00:05:30Z")
Well, you can see the moon when it’s illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough. The sun delivers about 1370 watts of power per square meter at the earth’s surface, a little more to the airless moon. Perhaps a square kilometer of that sort of illumination would be visible from earth. A square kilometer being a million square meters, you’d need at least a 1.37 billion watt laser. ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [November 9, 2007, 12:20am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/9 "2007-11-09T00:20:13Z")
Isaac Asimov wrote a short story about someone selling advertising space on Jupiter. Apparently, aliens often came to the outer solar system to admire our gas giants on their way from one place and another, so an alien corporation wanted to project an ad slogan (for some alien equivalent to Pepto Bismol, I think) across the cloud deck. The best part of the story was the title, “Buy Jupiter!” I hope that wasn’t a totally unwelcome interjection into this thread. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 9, 2007, 12:23am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/10 "2007-11-09T00:23:43Z")
Best time to do this is during a lunar eclipse. The sun won’t be visible to create light pollution, and the moon will be almost as dark as a new moon. Of course, whether people will think this is cool or annoying is a good question. I don’t think you’re going to be able to draw anything visible on a full moon. There’s a reason they don’t do laser shows in the daytime. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [November 9, 2007, 12:31am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/11 "2007-11-09T00:31:53Z")
Using a lunar eclipse as a canvas also occured to me as I was on my way home but I see I’ve been beaten to it. In any case, how far into [this list](http://en.wikipedia.org/wiki/List_of_lunar_eclipses#21st_century) can we go before somebody has both the engineering capability and the balls to give it a shot? ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [November 9, 2007, 12:32am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/12 "2007-11-09T00:32:51Z")
The path loss from the Earth to the Moon and back to the Earth is extremely high. When lasers are used to measure the distance between the Earth and Moon, using retroreflector arrays left on the Moon by the Apollo missions and a large telescope on Earth, they are detecting individual photons at the end of the journey, and not very many of them. See [http://physics.ucsd.edu/%7Etmurphy/apollo/apollo.html](http://physics.ucsd.edu/%7Etmurphy/apollo/apollo.html) for details. ---
**Author:** ![Rattlehead02](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rattlehead02/32/3944_2.png) [@Rattlehead02](https://boards.straightdope.com/u/Rattlehead02)\ **Post date:** [November 9, 2007, 12:48am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/13 "2007-11-09T00:48:41Z")
[QUOTE=Squink] Well, you can see the moon when it’s illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough. The sun delivers about 1370 watts of power per square meter at the earth’s surface, a little more to the airless moon. Perhaps a square kilometer of that sort of illumination would be visible from earth. A square kilometer being a million square meters, you’d need at least a **1.37 billion watt laser**. [/QUOTE] Yeah, but can you put that frickin laser on a shark’s head? Didn’t think so. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [November 9, 2007, 12:57am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/14 "2007-11-09T00:57:22Z")
[QUOTE=Saltire] Isaac Asimov wrote a short story about someone selling advertising space on Jupiter. Apparently, aliens often came to the outer solar system to admire our gas giants on their way from one place and another, so an alien corporation wanted to project an ad slogan (for some alien equivalent to Pepto Bismol, I think) across the cloud deck. The best part of the story was the title, “Buy Jupiter!” I hope that wasn’t a totally unwelcome interjection into this thread. [/QUOTE] That was my first thought when opening this thread. Great story. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [November 9, 2007, 1:03am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/15 "2007-11-09T01:03:12Z")
[QUOTE=Squink] A square kilometer being a million square meters, you’d need at least a 1.37 billion watt laser. [/QUOTE] Well, heck, by the time that’s possible, the adverts can be for “Mr. Fusion.” ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [November 9, 2007, 1:19am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/16 "2007-11-09T01:19:53Z")
[QUOTE=Squink] Well, you can see the moon when it’s illumined by the sun, so if you could build a laser to project the same amount of light onto a dark piece of the moon, it should be visible from earth; providing of course that the illumined area is large enough. The sun delivers about 1370 watts of power per square meter at the earth’s surface, a little more to the airless moon. Perhaps a square kilometer of that sort of illumination would be visible from earth. A square kilometer being a million square meters, you’d need at least a 1.37 billion watt laser. [/QUOTE] Well no, because you could see the advert at a lot less light intensity than the full moon. I mean, you can often see the “dark” portion of a nearly new moon lit up by earthshine, which is sunlight that has bounced off the earth, up to the moon, then reflected back to earth. I’d guesstimate that the intensity is maybe a hundredth of the full moon intensity, so maybe you’d only need a 14 megawatt laser… ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [November 9, 2007, 1:33am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/17 "2007-11-09T01:33:28Z")
[QUOTE=Colophon] so maybe you’d only need a 14 megawatt laser… [/QUOTE] Sorry pal, all we got is what you see here. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 9, 2007, 2:24am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/18 "2007-11-09T02:24:14Z")
[QUOTE=Colophon] the “dark” portion of a nearly new moon lit up by earthshine … so maybe you’d only need a 14 megawatt laser… [/QUOTE] [This dubious source](http://mobile.orbit.zkm.de/?q=node/165) claims that earthshine on the moon runs at about 0.1 W/sq.meter. To outshine that, you’d need 100,000 watts per square kilometer of lunar surface. Your 14 megawatt laser would sufice for 140 square kilometers; a circle 44.5 km in diameter. At 384400 kilometers distance, that circle would subtend a visual angle of 0.0066 degrees. That’s a pretty small spot of earthshine to be picking out! ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [November 9, 2007, 2:31am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/19 "2007-11-09T02:31:02Z")
I didn’t see anyone mention it yet, but the moon isn’t a flat surface. Most light that reached it from the Earth would be reflected at an odd angle. Consider the point above about the mirrors left on the surface only reflecting a few photons and extrapolate for a grey surface with boulders and craters and dust. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [November 9, 2007, 3:21am UTC](https://boards.straightdope.com/t/laser-art-on-the-moon/425725/20 "2007-11-09T03:21:44Z")
[QUOTE=USCDiver] I didn’t see anyone mention it yet, but the moon isn’t a flat surface. Most light that reached it from the Earth would be reflected at an odd angle. Consider the point above about the mirrors left on the surface only reflecting a few photons and extrapolate for a grey surface with boulders and craters and dust. [/QUOTE] Actually, my first thought was about how lousy a reflective surface the moon would be, aside from its convexity, or concavity, whichever – I can never keep them straight. :p. So, I would suggest a scattering of some kind of highly reflective powder over the lunar surface. I would imagine you could significantly reduce the power requirements by making the moon a more efficient “projection screen”. Similarly, I’m thinking you want orbital lasers. Besides getting rid of atmospheric scatter – well, except for what is reflected back _from_ he moon, you could avoid some other problems. Like possibly incinerating any aircraft or birds that fly over the beams. And bringing down the wrath of that whole Global Warming gang, cuz I also imagine that passing the beams through the atmosphere would involve some heating, very minor I’m sure. And I would like to see some kind of animation, not just still images. You can have early-evning family-friendly Disneyesque animation (remember _The Sorcerer’s Apprentice_?), and late-night adult porn. If you can figure out a scheme where you need special glasses to see it, you might get into pay-per view. You might be able to get the Defense Department or the CIA to underwrite the whole thing. I’m pretty sure that with powerful lasers like you would need to do this, if you could spin the orbital lasers around you could do interesting things to the earth’s surface too. [Next page](https://boards.straightdope.com/t/laser-art-on-the-moon/425725.md?page=2)