Is there anything (short of a nuclear detonation which was covered in a previous thread) that you could do on the Moon that could be seen on Earth with the naked eye?
I would prefer answers of things that could actually be done with our current technology but feel free to go crazy with the wild stuff if you must.
ETA: And by “our current technology” I mean in a launch or two. A million Apollo launches with light bulbs might do it but that is not really feasible.
I’m wondering if you put really REALLY powerful laser(s) in orbit around the moon, then using computer controlled mirrors, turn the night-side surface of the crescent moon (or a new moon) into a giant Laserama? Of course, the next challenge would be transmitting Pink Floyd’s Dark Side of the Moon into every home on earth.
I would bet that the one could see the light from a 100W Argon laser on the moon if it was aimed directly at the viewer on Earth.
“In space, no one can hear you play The Dark Side of the Moon”
What area would that beam cover on Earth? (and what size is a 100W argon laser projector, btw?)
I’m reminded of another recent thread; how about we set off a nuke on (or near the surface of) the moon?
Also: we already shine lasers on the moon, but they bounce off mirrors and aren’t visible with the naked eye. Lunar Laser Ranging experiments - Wikipedia
Read Asimov’s “Buy Jupiter!”
I would think it would be easy to land a light on the moon that was bright enough to be seen when it is in Earth’s shadow. Wouldn’t do it during Ramadan though.
Around a mile or less. With good collimation you could probably get it down to hundreds of feet. A 5mW green laser is blindingly bright at 1 mile - a 100W laser is 20,000 times more powerful, so if it is placed 250,000 times farther away it should be easily visible. A laser this size might be the size of a refrigerator.
As for the comment that “we already shine lasers on the moon”, I was proposing a moon-based laser.
I think you mean Heinlein’s “The Man who Sold the Moon”. For the non-SF fans in the audience, an entrepreneur funding the first manned mission to the Moon sells the advertising rights on the surface to a soft drink company (which has no intentions of using said rights, but intends to keep them out of the hands of their competitor). The protagonist convinces the CEO that it would be possible, with large fireworks filled with graphite, to draw the competitor’s logo on the surface in a way that would be visible and readable from Earth.
It’s not actually clear from the story whether the protagonist actually thought it was possible, or if he was just bluffing himself more funding.
Arthur C. Clarke wrote a very similar story (Watch This Space). I wonder which came first.
I think he actually means “Buy Jupiter” from Asimov. A great story, even though it is so short I could probably cut and paste here if it weren’t a copyright violation. In short, alien race contacts Earth wanting to buy Jupiter as a billboard.
ETA: 1958 that story, btw.
Actually, you would want the area covered to be as wide as possible, I presume. If you are doing this type of stuff, you want more people to see it, not less.
Now, be them lights or lasers or explosions, they are all very small phenomena no matter how bright they are. How would that look from Earth? A single pinpoint of light? About the same as a star (which are larger but a lot further away)?
I don’t think we have any continuous light sources that are capable of visibly illuminating an area on the Moon. The only way that I can think of being able to see a light source from the moon is to shine a laser directly at the earth, and make the beam as tight as possible. It would look like a bright green pinpoint.
The best way is to use the surface of the moon as a canvas, and “paint” it with laser light while the moon is in shadow.
I’m not sure how powerful a laser you would need. Probably an array of lasers in geosynchronous orbit around the moon, to complete an image of some sort. Or even just highlight the areas where the Apollo missions landed. Might be a good stunt for the 100th anniversary of Apollo 11.
I’m not sure either, but here’s some back of the envelope numbers. Earth gets about 1,000 W from the sun per square meter; the moon must get about the same amount. The moon’s albedo is only 7%, so artificially reproducing normal moonshine would be about 70W per square meter. That’s not so bad per square meter, but you’d have to light up many thousands of square meters to make something visible as even a small dot.
When I was a kid the Air Force flew a plane over my community in a test of an airborne light to illuminate large areas. This would certainly have been seen from the moon in shadow as easily as we can see cities lit up at night as viewed from satellites. It was done in the 70’s and I can’t seem to google the event.
In other words, sitting on the Earth?
Its gonna be somewhere between 10s and thousands of square miles and maybe even way more than that for just a “dot”.