# Being seen on the Moon. **URL:** \ **Category:** Factual Questions\ **Created:** [August 16, 2009, 5:47pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641 "2009-08-16T17:47:44Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [August 18, 2009, 6:02am UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/21 "2009-08-18T06:02:59Z")
> [@Chronos](#): > > In other words, sitting on the Earth? :smack: ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [August 18, 2009, 6:09am UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/22 "2009-08-18T06:09:29Z")
Is there a way to build a giant stencil between the sun and moon (much, much closer to the moon) to create a “shadow puppet” on the lit surface? Of course, the smaller you make the silhouette, the blurrier the result because the penumbra would increase. But maybe you could get a huge, blurry dot out of the deal? ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [August 18, 2009, 6:14am UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/23 "2009-08-18T06:14:03Z")
Also, you could probably send a small fleet of regolith tilling, solar powered robots that could trace out huge, dark tracks of lines to create whatever image you want. It’d take months, if not years, but it’s probably the most doable. Though, defacing the moon so permanently would be an abomination. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [August 18, 2009, 2:09pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/24 "2009-08-18T14:09:00Z")
In the recent Will Smith flawed-superhero movie _Hancock_, he somehow carved and illuminated a charity’s logo on the face of the Moon, large enough so that it could be seen from the surface of the Earth. Just a throwaway gag at the end of the movie, I know, but I winced a little when I saw it - that kind of damage to the lunar surface might be reversible, kinda, but it’d never be the same afterwards. ---
**Author:** ![Gyrate](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gyrate/32/3588_2.png) [@Gyrate](https://boards.straightdope.com/u/Gyrate)\ **Post date:** [August 18, 2009, 2:16pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/25 "2009-08-18T14:16:09Z")
And then there’s [Chairface Chippendale](http://en.wikipedia.org/wiki/Chairface_Chippendale)… > [@](#): > > In one episode, Chairface attempts to write his name onto the surface of the moon with a powerful laser. He only manages to write the letters “CHA” from “CHAIR”, and even then only part of the “A”, before he is thwarted by the Tick. Later, the “C” is destroyed by the Tick as part of a partially successful mission to return the moon to the way it used to be. As a running gag, the “HA” remains inscribed on the moon throughout the rest of the episodes of the series. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [August 18, 2009, 5:56pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/26 "2009-08-18T17:56:46Z")
> [@billfish678](#): > > Its gonna be somewhere between 10s and thousands of square miles and maybe even way more than that for just a “dot”. Yeah, something like that… depending on whether we want it visible to the naked eye or just visible at all. According to [http://www.mazelife.com/blog/read/ads-on-the-moon/](http://www.mazelife.com/blog/read/ads-on-the-moon/) you’d need about 100 meters to be visible to the Hubble telescope (so 10,000 sq meters) or about 220 km for the naked eye (so about 50 billion sq meters). ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 18, 2009, 7:15pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/27 "2009-08-18T19:15:02Z")
Note that that’s the size you’d need for a _resolved_ dot. You could still see a feature much smaller than that as a point source, if it was bright enough. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [August 18, 2009, 7:26pm UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/28 "2009-08-18T19:26:34Z")
> [@Chronos](#): > > Note that that’s the size you’d need for a _resolved_ dot. You could still see a feature much smaller than that as a point source, if it was bright enough. True enough. But if your illuminated area is significantly smaller than the smallest dot you can resolve, the energy level per area has to go up since its gonna be spread over that dot size by your eye anyway. Lets say you need a 100 gazilla watts to see your barely visually resolved dot thats a 100 miles across on the moon. If you illuminate an actual area on the moon thats only one mile across instead, your eye is still gonna see that spot as a 100 miles across. And you will still need a 100 gazilla watts to see it. I know you know that. Just pointing it out for folks that may not. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [August 19, 2009, 12:24am UTC](https://boards.straightdope.com/t/being-seen-on-the-moon/506641/29 "2009-08-19T00:24:37Z")
> [@billfish678](#): > > I know you know that. Just pointing it out for folks that may not. I don’t think I did. It made so much sense that I feel like I could have figured it out by myself but I sure hadn’t. Thanks for pointing that out. [Previous page](https://boards.straightdope.com/t/being-seen-on-the-moon/506641.md?page=1)