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What Would Happen If the Moon Crashed To Earth?
angkor writes: "What would happen if the Moon crashed into the Earth? We'd die. But there seem to be a lot of variables involved in answering this. I wonder if /.ers have any other ideas..."
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The subject says it all really...
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The moon must have vast amounts of gravitational potential energy (just think how much energy would be needed to raise a moon sized chunk of the earth into orbit). If we could move the moon is a couple of thousand kilometers, nobody would mind (except for people who want to keep the lunar month the same). But does anyone know of a way to actually convert this GPE into useful energy?
The article pretty much covered why the moon won't ever hit the Earth (and what would happen if Q snapped his fingers and it did), so I won't touch that.
However, this does remind me of a very, very bizzare conversation I and several others had a couple of years back (while waiting for food at a restaurant, and pondering the rolls).
Q: What would happen if you had an entire planet made out of bread?
Getting the answer was a very amusing thought-experiment. It turns out that you'd eventually end up with a bacteria-infested planet with a large diamond core, a mantle of uncertain composition, a crust of tar with seas of complex hydrocarbons and carbohydrates, and an atmosphere of methane and water vapour.
So, I invite similarly bored slashdotters to consider similar questions involving other materials, or other interesting celestial thought-experiments.
...and he lives at the North Pole and would save the world from the impending moon.
The only physics Computer Science majors should comment on is maybe a brief discussion on the issues of electrons, physical limitations of spinning platters, and maybe what would happen if the dvd were to crash into the cd-rom.
Patche says, "You will attract more flies with honey than vinegar... but who wants flies?
What about Pluto and Charon? Aren't they closer in size to each other than Earth and the Moon?
Yes; check out Nine Planets (look at Earth, The Moon, Pluto and Charon). Here are the diameters:
__________ Diameter
Pluto _____ 2274 km
Charon ____ 1172 km
Earth ____ 12756 km
The Moon __ 3476 km
This is a diameter ratio of about 1/2 for Charon/Pluto and 1/4 for Moon/Earth.
...indicate that, assuming the Moon's orbital momentum were bled off at some reasonable (!) rate, that it would spend sufficient time within its Roche limit (5.5*2.42/3.34 = ~4 earth radii) to be torn to bits and redistributed into a massive, chunky ring. Once that transformation was accomplished, the Earth's surface would rapidly restabilize; since the ring would have a somewhat evenly distributed mass, its major tidal effect would be to increase Earth's equatorial bulge.
Of course, the large number of collisions in NEO among kilometer-and-greater-diameter objects would result in many thousands of catastrophic KT-magnitude impacts, meaning that any current life on earth would be kaput without a primary lunar impact ever occurring.
Mr. Bailey answered this question well, but seemed to believe that this kind of event was impossible. I'd suggest running an N-body simulation in which a small, massive object such as a black hole passes near the Earth-Moon system, in such a way as to impart a differential acceleration to the two bodies. It's easy to find (by trial and error, if need be) the appropriate criteria for a fly-by that would drop the Moon right in our laps, with little or no lateral motion. I'd guess that this was probably the kind of impact that the questioner envisioned.
Remind anyone else of the climactic scene of When Worlds Collide?
The curent theory of moon formation is that when Earth has about 90% of it's current mass (~4.5 billion years ago, or 50ma after the start of the solar system), a planetoid about the size of mars hit at a glancing angle. This gave us an enhanced metal core (original core+core of the other planet), blasted enough rock vapour into space to create the moon, and melted the entire planet.
It's safe to say that if you were on the surface of the earth prior to this, watching the incoming planet, you'd probably need a change of underwear.
regarding your hypothetical "bread-planet"
why a diamond core ?
oxygen is heavier, and at large densities you would probably get some metalic phase which is not solid state.
come to think of it hyper-dense carbon should also be different than usual diamond, as the E part of the Gibbs free energy F=E-TS will be mostly a function of the density (r^-12 part of leonard-gibbs potential) and not of the chemical connection. (=> disordered state, pseudo-liquid)
Working for necessity's mother.
Will the moon crash into earth if we continue to extract energy via tidal waves?
why a diamond core ?
:)
Because diamond is the more compact form of carbon (hence its formation from other allotropes under pressure), and I'm assuming that carbon is more abundant than the other elements composing bread.
oxygen is heavier, and at large densities you would probably get some metalic phase which is not solid state.
Hmm. Diamond outer core?
come to think of it hyper-dense carbon should also be different than usual diamond, as the E part of the Gibbs free energy F=E-TS will be mostly a function of the density (r^-12 part of leonard-gibbs potential) and not of the chemical connection. (=> disordered state, pseudo-liquid)
My understanding was that diamond was stable up to surprisingly high pressure. The only thing that would be more compact than it would probably be some kind of metallic state with a spherical close-pack structure. Is a planet's core pressure enough to force diamond to convert to that kind of structure? (I don't have a phase diagram of carbon's allotropes handy.)
then we'd all be toast!!
I was listening to an NPR show quite
awhile ago, (about 1-1 1/2 years ago i believe)
They were talking about the moon ad said
something to the effect that it will eventually
drift out of earth's orbit.
I believe the number quoted was somewhere between
100,000 to 150,000 years from now.....
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----
Striving to put right what once went wrong, and hoping each time that his next leap, will be the leap ho
>It might get further away, but it will still be around when the Sun goes Nova and swallows it all anyhow.
Except the earth will probably not be swallowed when the sun goes off main sequence. It turns out that the astronomers who first suggested this neglected the fact that the sun will have radiated a significant portion of its mass as light during the billions of years left in its lifespan. As the sun loses its mass, the planets will gradually move further away from the sun, so the Earth will live to see the Sun become a white dwarf. Still, the Earth will be pretty toasty by that time, and will probably have lost its atmosphere to the solar wind long before that (once the Earth's core cools and we lose our magnetosphere.)
Given that we know, for certain, that the moon is made of cheese (this is as obvious as the fact that the universe revolves around the earth), the results are simply deduced:
We would all be cheesed off.
Thank you. Thank you Very Much.
The first has already been mentioned, and that is that Charon and Pluto are closer in size than the Earth and Moon. The second I don't think has been mentioned yet: the moon does not have "a cold, solid core". The August issue of Discover magazine points out a few reasons why we beleive that the Moons core is at least partially molten in the article "Nuclear Planet" (well, something like that, the title may have been a bit different).
Never underestimate the power of human stupidity.
According to an N-body simulation in which a small, massive object such as a black hole passes near the Earth-Moon system, in such a way as to impart a differential acceleration to the two bodies. The moon would drop from orbit and collide with a force of 10000 kilodinojoules into your eye like a big-a pizza pie.
That's amore.
At that point you'll sing "Vita Bella".
Cake or Death? Cake Please!
You could accelerate the Earth if you wanted to, and generate electricity. This requires something like a 3- or 4-step process:
- Lift lunar rock off using a long beanstalk extending toward Earth.
- Drop material from the end of the beanstalk into an elliptical orbit falling in toward Earth, preferably an orbit with its perigee below Earth's geosynchronous orbit.
- This time using a beanstalk coming up from Earth, catch this material with a device which converts its excess kinetic energy to electricity. The transfer of angular momentum also accelerates Earth's rotation.
- If you've caught this stuff at or below geosync, you can just lower it down to Earth and convert the remaining potential energy to electricity (like a hydro turbine, only with moon rocks). This process transfers even more angular momentum to Earth.
What happens to the Moon in this? The process of sending material Earthward on the first beanstalk conserves angular momentum, so the rest of the Moon moves outward and slows down, making the month longer.Scientists restrict study to entire physical universe; creationist
Fruit flies are attracted to vinegar, and if you want them out of your kitchen....
Scientists restrict study to entire physical universe; creationist
didn't anyone see the scientifically accurate movie The Time Machine. When the moon collides with the earth, part of the population will flee underground and evolve into these freaky hyper-predator humanoids called morlocks. The fragmented remains of the surface-dwelling humans will create an idyllic proto society with neo-lithic science and incredible basket weaving skills.
sheesh. i don't know why questions like this even get posted. The movie only just came out this spring.
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There's interesting circumstantial evidence that Earth's days were once longer. People and animals left to themselves in deep cave systems (ie completely isolated from sunlight) seem to all settle on a 25-hour day.
Velikovsky's cosmic ballet explains this rather well. It's a pity it's become such an albatross that nobody's spending any time reworking it these days, because it seems fairly obvious (especially after Shoemaker-Levy and in light of things like Saturn's very young rings) that our solar system ain't the peaceful celestial meadow that many people like to make it out to be.
I for one would be a lot more comfortable knowing how other objects in my solar system behaved under borderline situations, and fear of being branded a nutcase seems to be stopping science in general from investigating a lot of interesting stuff along these lines.
Got time? Spend some of it coding or testing
Considering the moon is moving away from the earth, I think, if the moon were to crash into the earth, then pigs may fly, and hell just might freeze over as well...
Thats just a guess though...
is if the moon crashed into the earth and everyone died and no one was left behind to tell about it... would it still make a sound?
We'd all be dead. After that, nothing matters.
Really? Where did you see this evidence? Everything I've ever read points at a 19 hour day back in the early dinosaur days and slowing ever since then.
Sounds like the old musings of Dave (Milk Milk Milk!). He would walk up to random people on the street and fire off the following questions, high speed, non-stop:
Which way's up?
What color's blue?
What if the moon fell down?
What if people were little yellow squares and dogs were red circles?
What's your mom's name?
What's your dad's name?
What's your social security number?
What color is your cat?
What flavor is your dog?
What shape is your mailbox?
Earth == bread
Moon == cheese
Collision == very large grilled cheese sandwich.
Any sufficiently simple magic can be passed off as mere advanced technology.
So... Rrr, Doh!
I can't believe this. You all are making light of a very serious question involving mathematics of orbits, and what kind of long term solar system damage would occur should the moon (I assume we are talking about our moon, here), crash into the Earth. And all some of you do to answer this serious question is make jokes about things they learned from "Thundarr the Barbarian" or something. Well, not me.
.05%
I want to know the media angle.
This would be a godsend to Fox News and the New CNN. Ratings aplenty. All kinds of pundits speculating everything as the large death-ball looms closer. You heard me right: "death-ball." And people would be glued to their TVs, and advertising revenues would soar.
"Pepsi presents: Armageddon. The choice of a lost generation."
CNNfn would want to know how this would affect stock prices. There would be the usual gang of idiots all pointing their financial fingers in 20 different directions. Some would see the stock market plummet as people cashed out. Or leveled as people just gave up hope, because you can't take it with you. Maybe it would even increase, says a man who just bought 20billion shares of PepsiCo, because of all the ad revenue.
CSPAN, with both of their cameras on 24/7, would show the last senators and representatives discussing how THEY should get more disaster relief to their state. Senator Gramm has taken the floor, demanding more disaster relief since the DFW corridor has taken a beating as it is in the dying IT market and with their citizens appearing on every other episode of "C.O.P.S." And now this! Probably a liberal plot to move the tech corridor to Virginia, he says.
Fox news gets a poll:
- Thinks the world is going to end: 55%
- Thinks the world is going to recover: 22%
- Thinks the moon is made of a stinky green cheese: 62%
- Hopes it doesn't crash into their state: 95%
- Knows it doesn't matter where it crashes, the world will blow up anyway:
- Thinks Senator Gramm is made of a stinky green cheese: 12%
- Blames the Democrats: - 45%
- Blames the Republicans: - 45%
- Blames Senator Gramm: - 62%
- Blames the reduction of "Pro-gravity" initiatives: - 5%
- Said, "What moon?" - 10%
- Said, "No foolin'? Crashin' into the Earth? Damn!" - 10%
- Said, "I don't care, as long as I don't have to clean it up!" - 10%
- Thinks this will postpone the Oscars - 42%
- Thinks the polls are calculated incorrectly: - 129%
Nickelodeon will have a Linda Ellerbee special called, "You didn't eat enough vegetables, and now we're all gonna die, you brats!" Sesame Street will have a very special episode where Dr. Philip Morrison explains gravity wells to Elmo. Parents petition books stores to remove the "inappropriate and disturbing" book, "Good Night Moon."
Howard Stern will admit it was all an act to detract from his effeminate curly hair. Then he tells fart jokes until the studio or the moon's crash cuts him off the air.
Evangelical Christians will be smug, say the bible predicted this with a lot of vague interpretations, and eventually blame gay people. Gay people will blame stereotypes. Stereotypes will blame the press, who will blame each other on the next 20/20. Jack Chick will suddenly admit his campaign and tracts were all a joke started by a bet with the late Anton LaVey on who could repel the most people from Christianity in the shortest time possible. He won.
In the end, the media will finally get what it wants, and while the moon and the Earth smash into each other like melons in a mosh pit, people will still be arguing about whether this is all just hype.
You can work these things out for yourself using simple algebra. Just remember that angular momentum (m * R cross v) is a constant, and energy (1/2 m v^2 - m1m2g/r) is also constant. If only only consider conditions where v and R are perpendicular (circular orbit, or periapsis and apoapsis of an elliptical orbit) given the speed and radius at one point you can solve for the condition at the other; the only thing you have to solve is a slightly complex quadratic.
Scientists restrict study to entire physical universe; creationist
The question should be "What would happen if the Earth crashed into the Moon?"...
Geesh, how do you expect to get intelligent answers, when you ask the wrong silly question.
RTFM (Reverse the Freaking Moon)
Been mention here before, but here's a lengthy read - part of a larger site from someone who has a great deal of time on his hands.