Actually, I just noticed you (badastro) joined in April :o, so can you change that greeting to a wish that you’d jump in more often than four posts in seven months.
HenrySpencer (needing more sleep).
Bad astronomer, I think that you are overestimating the energy required to destroy the moon. I dont want the thing vaporized, though it would be nice. IF (half of it) it must rain down in big chunks, killing millions, so be it. Surely their are enough nukes to shatter it into more managable bits?
We could get a really long anchor and get the moon to drag it around the earth till its orbit decays and it comes home to papa.Or if we could borrow a warp drive and run a ship through it at greater than light speeds , or a hyperdrive…(i always wondered why they didnt blow up the deathstar that way). If we could put enough space junk in its path it might hasten its departure from orbit.
oh, the possibilities…
We could just paint it black, and pretend.
Better- Paint it pink and get a small SEP field generator. (Hitchhikers guide)
I am truly disturbed by this thread (as opposed to all the other things on this 'board that would disturb, say, your vocational counselors or your parents, should they stumble across it.)
I have finally despaired of the available US political parties, and have incorporated “The Friends of the Moon” as a political party in Alaska… (coming soon to a mall near you.)
I have been a professional poet for 23 years. If you take the moon away from me as a topic, I’ll have nothing to write about except my penis…
Please, reconsider this drastic manuever. The consequences are more dire than you imagine…
You could write about the glorius destruction of the moon, and how the destruction of the moon is symbolic of the destruction mankind inflicts on its self. Or for a feminist perspective you could write about how the moon represents the female and the rocket/whatever used to destroy the moon represents the male. That way you can still write about your penis, whilst reminiscing on the moon. If we blow it up you will be among the last generation of poets to use the moon as a muse. This would surely boost your profile many times. In summary- is not the fleeting beauty of the moons destruction more poignant than the enduring eye in the sky?
Its watching me i tell you. ALL THE TIME. but i’ll show it hehe. It wont be laughing at me much longer. MUAHAHAHAHAHAHA!!!
First, to Henry: you’re happy I’m here? I’ve been reading your level-headed posts to sci.astro for years. I’m glad you’re here! I don’t post much because for some reason it takes forever for these threads to load. Sometimes I get hits on my website from these threads so I take a look to see what’s going on.
Second, to the thread: all the nukes we have ain’t gonna do much to the Moon. We could make a nice crater, I suppose, and screw up hope for future colonization, but remember, the Moon is big. A single asteroid 1 kilometer across moving at typical orbital speeds would dwarf our nuclear aresenal if it impacted, yet it would only leave a crater a few tens of kilometers across.
Face it. We think we’re hot stuff, but the Universe is vastly bigger, older, more powerful and patient than we are.
There was a calculation og how much energy would be required to blow up Alderaan in The American Journal of Physics back when Star Wars first came out in 1977. I don’t recall the numbers, but it’s in line with the magnitudes The Bad Astronomer suggests. It’s good to see that the AJP tackles these important questions.
Well, we obviously need a less conventional solution. Nukes wont cut it. For the moment i am out of ideas, unless Dr Evil and spare us a ‘laser’.
Well obviously Bad Astronomer has given you enough hints about how to do it. First, you find a near earth orbit asteroid or comet, at least 100 kilometers in size (please don’t ask me to do the calcs). Then, use one of the ideas for nudging asteroids OUT of earth collision orbits to push it INTO a collision course with the moon (as if that wouldn’t nearly be impossible). Sit back, watch the fireworks, and what’s left will probably take a few million years to reform.
If anybody asks, you didn’t hear this from me.
So if we can move the moon with the aid of a 100km rock, I take it that we can set that rock on a collision path, by the way of a well aimed blow from a 10km rock. A 1km rock should be able to do that job, aided by a precise blow from a 100m rock.
So basically to move the moon all we need is a small stone thrown very very accurately.
(Surprised someone on this site hasn’t already done the math)
The quickest way, as demonstrated in Star Trek: Generations, is trilithium shot into the sun. That took out a whole planet.
Oh, you mean we were suppoed to live after destroying the moon?
Back to the original question about the effects of blowing up the moon. There was a math professor at Iowa State University thatmade this proposal suggesting it would solve all of mankinds problems. I only remember this for having been there. I just think he said it to get published.
The Bad Astronomer’s numbers look good, but there’s a much easier way to blow up the Moon than with warheads - just push it into the Sun. My cursory calculations state that it will take no more than 1.8×10[sup]13[/sup] Megatons of Energy to “ionize” the Earth and send the Moon to its fiery doom. That’s only 60% of the Energy needed to do it directly. If we covered the Moon with 10% efficient solar panels, we could draw that much Energy from the Sun in only 41 Million years. Actually less, since as time went on, we’d be rocketing the Moon closer and closer to the Sun, so the panels would pick up more Energy. All in all, a foolproof plan.
I’m afraid I disagree with you, Achernar. It must take more energy to vaporize the Earth than the Moon, and by quite a bit. It has 81 times the mass of the Moon, so it takes 81*81 = 6500 times the energy to blow up the Earth.
Worse, that won’t change things much with the Moon. The Moon orbits the Earth at roughly 1 km/sec. The Earth (and therefore the Moon as well) orbits the Sun at about 29 km/sec. If you were to magically whisk away the Earth, the Moon would still happily orbit the Sun, though on a slightly more elliptical orbit.
To plunge the Moon into the Sun, you would need to slow it down enough to fall in. That is essentially the same as stopping it dead in its tracks. Using good old energy = 1/2 * mass * velocity^2, I calculate that will take 7x10^15 megatons, or 200 times the energy needed to simply vaporize the Moon. Better just to blow it up.
There is a way out. If we just want to get rid of the Moon and not necessarily destroy it, we would only need to give it a small kick to give it escape velocity. Escape velocity is 1.4 times the circular velocity, so if we can get it moving just .4 km/sec faster, it’ll leave the Earth on its own. That’s only 1.5 x 10^12 megatons, or 1/20 what it takes to destroy it.
The only problem then is that it will still be in roughly the same orbit as the Earth. Gravity from the other planets will perturb it into different orbits, and eventually it might get onto a collision course with us. That would be BAD. It might be better to spend the extra energy and vaporize it.
Solar radiation is 1353 watts/m^2 and the Lunar radius = 1738 km, so the Moon receives 1.284E13 kWatts. There are 8766 hours / year, so this is 1.125E17 kWatt-hours / year.
Using 1 kiloton = 1.162E6 kWatt-hours, this becomes 9.69E10 kilotons/year = 9.69E7 megatons/year
The Bad Astronomer says we need 1.5E12 megatons, so this will take 1.5E12 / 9.69E7 = 15,500 years.
I’m telling you, mirrors are the way to go.
As we gradually increase the Moon’s orbit radius, the effect of Venus’s gravity becomes more important. Eventually, we’ll just need one small asteroid or Nuke to tip it out of Earth orbit. Timing it right, we should be able to use Venus to direct the Moon into the Sun. Problem solved.
Of course, a better solution would be to leave it in orbit around Venus, slowing it down using the same mirrors. Some people (e.g. Dr.Pinky, and I’m sure at least one or two others) might not like destroying the Moon outright. Plus, if it turns out we really do need the Moon, we’ll be able to get it back.
If you ionize a Hydrogen atom, you give the electron enough Energy to escape the proton’s pull. I thought it would be terribly clever of me to refer to the giving of the Moon necessary escape velocity as ionization. Now I realize it was just confusing. I don’t want to destroy the Earth, at least not until I leave. So, we had the same idea about shooting the Moon off, but your solution is a bit more elegant and conservative. I was just counting the brute force needed to push it. Your numbers look better than mine, too, so I concur.
sweet progress! We’re down from 41 million years to a possible 15,500 with mirrors. Lets take that a bit further and get it down to say… 20 years. I want to be able to watch it happen. Who will remember in 10000 years? no one. Especially if we really do need the moon. 7E15 megatons for destruction and 1.5E12 for movement, hopefully into the sun. Now that would be a solar flare. Or would it? if we put the moon into the sun, would you be able to see it from earth?
If we spent 20 years just making nukes would we get enough energy to move te moon?
Welcome to the SDMB, Bad Astronomer! I have been reading your website for a long time.
What I haven’t seen discussed in this thread is what to do with the debris left over when our destroy-the-moon scheme is complete. Perhaps some of the debris would fall to earth, and some might end up in solar orbit, but wouldn’t a sizable proportion end up as a ring around the planet, a la Saturn (and the other gas giants?)
One word: Bitchin’! 
I hereby volunteer all the nuclear weapons I own to the cause.
Let’s just do it the good ole fashion way! Build a huge mobile pressurized tent, get some shovels and force convicts and soccer mom’s to start digging. Surely we could move enough dirt from one spot to another to make the moon wobble, or better yet, just jettisson the crap out into space, or send huge chunks of it down to earth so we can use it for our own environment diminishing purposes. Hell, if we can destroy our own environment, I’m sure we can destroy the moon!
The Universe may be bigger and more patient, but we got a big budget surplus, and not to mention too many convicts and soccer moms!
Who knows, maybe we could dig a whole through the center of it and make it look like a big donut, similar to Ringworld if you know what I mean!
If we can’t blow it up, or knock it out of orbit, I think we should at least change it up some, make it really obscene or something! 
Nukes? Bahhh… Rockets? Nah… Mirrors? We’re not boyscouts, were Americans!
Let’s do it with what this country was built on, good old sweat and blood, and ummm Slavery? Damn, I gotta rethink that one. (Note: I hold no prejudices or Bias, the previous was meant as a satirical but pathetic poke at our history)