What Would Happen If the Moon Crashed To Earth? 68
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..."
The moon is currently moving away from us (Score:2)
Re:The moon is currently moving away from us (Score:2, Interesting)
Re:The moon is currently moving away from us (Score:1, Interesting)
(to get this @#*&% link to work, remove the space between the "s" and the "t" in "s teals")
Re:The moon is currently moving away from us (Score:1, Funny)
Re:The moon is currently moving away from us (Score:2)
One interesting fact he mentioned is that the moon's gravity is very slowly lengthening the Earth's day, something that will probably have a significant impact on life on the planet if it continues for long enough.
Re:The moon is currently moving away from us (Score:1)
we may finally get the 25th Hour!@!@#$ [slashdot.org]
Re:Can't we use this for energy? (Score:1)
Re:Can't we use this for energy? (Score:1)
Unfortunately, this is hard to do as the Earth spins once in every 24 hrs (relative to the Sun) while the Moon orbits the Earth in a month. So, gathering wave power actually cashes in on the Earth's spin energy, moving the Moon out.
The only way to do it would be to build a giant ball on an arm pivoting on the North (or South) pole and keep it 90 degrees out of phase with the Moon, so the Moon's gravity would always pull it forward. It would do one RPM (revolution per month!) You could put a generator on the arm, and tap out the power, which would slow the Moon down in its orbit, and gradually lower it toward the Earth.
Much easier is to put a lot of nukes on the Moon [planetark.org], and beam microwave energy back to Earth. If the occasional reator blows up, it is no big deal on the Moon.
Re:Can't we use this for energy? (Score:2)
Are you KIDDING!?!
Didn't they have TV [space1999.net] where you grew up? Or are you one of those whipper-snappers who is too young to remember [aol.com]?
Not the way you think, and more ways too. (Score:2)
You could accelerate the Earth if you wanted to, and generate electricity. This requires something like a 3- or 4-step process:
Re:Not the way you think, and more ways too. (Score:1)
Also, "so the rest of the Moon moves outward and slows down," seems wrong. Speeding up the Moon would move its orbit outward.
Ironing out more wrinkles (Score:2)
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.
Surreal celestial questions. (Score:5, Funny)
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.
Re:Surreal celestial questions. (Score:1)
"We've just landed here on what cap troopers are calling the 'Big Bun' with the 6th Mobile Infantry Division. It's an ugly planet, a bread planet, a planet hostile to life as we know it...AAAAAAAAARRRRRGGGHHH!!!"
Seriously, though, wouldn't its moon be a huge pat of butter?
Re: why diamond core ? (Score:1)
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)
Re: why diamond core ? (Score:2)
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.)
Re:Surreal celestial questions. (Score:1)
Re:Surreal celestial questions. (Score:1)
On a slightly related note, check out this article [slashdot.org] from last month.
Re:Surreal celestial questions. (Score:2)
Not that big. We can form diamonds in hydraulic presses, so the pressure's pretty low on a planetary scale.
On a slightly related note, check out this article [slashdot.org] from last month.
That article made my head hurt
Re:Surreal celestial questions. (Score:1)
Re:Surreal celestial questions. (Score:1)
Add the heat from a moon collision, and you get: (Score:2, Funny)
Moon == cheese
Collision == very large grilled cheese sandwich.
Re:Surreal celestial questions. (Score:2)
What happens if you heat bread in a vacuum? If you heat bread in atmosphere, it gets toasted -- the surface of the bread oxidizes, basically. In a vacuum, however, it would simply get warmer but there shouldn't be any kind of chemical reaction until it gets to -- dare I say it? -- the melting point of bread!
So in theory, bread heated in a vacuum should eventually become liquid or vapor. Am I even close to being right?
Re:Surreal celestial questions. (Score:2)
I'm nowhere near an expert on this kind of thing, but I believe there would be several intermediate steps before the bread turned into vapour.
The reason is that bread is made up of a bunch of different elements, and all have their own temperatures at which they turn into liquid and then gas. Thus, if you increased the temperature slowly enough, you could see some elements seperating from the bread mass before others.
Re:Surreal celestial questions. (Score:2)
Unforunately, bread doesn't do anything this fun when heated
In vacuum or in an inert atmosphere, you'd get chemical transformations long before any melting occurred. Sugar and starches would shed water to become mostly carbon, and the other varied building blocks would turn the bread loaf into something resembling tar before it started boiling.
In vacuum, the water would diffuse into space immediately, and the other hydrocarbons would follow slowly (much lower vapour pressure, so less mass flow). You might have a brittle sponge-like mass of carbon left over.
In an inert atmosphere at normal pressures, the water will boil off as steam, but as long as you're in a closed container most of the medium-to-heavy hydrocarbons will stay put once a small amount has boiled into the air (it stops boiling when the partial pressure of hydrocabons in the air equals the vapour pressure).
Kind of neat to see what would result, though
[NOTE: I can't emphasize too much how much respect you should have for concentrated acids. Wear protective gear, and use long tongs if possible, because concentrated sulphuric will eat through almost anything except glass and ceramics.]
Re:Surreal celestial questions. (Score:2)
And do this under a fume hood, because boiling acid vapour is Not Nice.
Yes, Virginia there is a Santa Claus (Score:1)
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.
Quip (Score:1)
pluto & charon? (Score:3, Interesting)
What about Pluto and Charon? Aren't they closer in size to each other than Earth and the Moon?
Yes; check out Nine Planets [arizona.edu] (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.
Re:pluto & charon? (Score:2)
We could stage a science coup d'tat and have it reinstated. You get the pitchforks, I'll bring the bunsen burners.
Re:pluto & charon? (Score:1)
That's no moon. It's a space station
My own CNC's (cocktail napkin calculations)... (Score:5, Informative)
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 [imdb.com]?
Re:My own CNC's (cocktail napkin calculations)... (Score:1)
Re:My own CNC's (cocktail napkin calculations)... (Score:2)
What really happened.. (Score:3, Interesting)
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.
Re:Sort this out for me.. (Score:1)
Effectively, tidal energy energy works by slowing down the rotation of the earth, using the bulge in the water level raised by lunar tides. As the earth is rotating faster than the moon is orbiting, and as angular momentum is conserved, this works to *raise* the orbit of the moon.
This is already happening due to tidal friction; extracting tidal energy on a huge scale would perhaps speed the process a fraction, but only a fraction.
If the earth were a big spherical bread loaf... (Score:1)
Re: Earth destroyed as a Round Loaf (Score:1)
NPR - moon will drift away (Score:1)
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.....
Re:NPR - moon will drift away (Score:2)
awhile ago,
They were talking about the moon and 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..... *)
My understanding is that the moon is drifting away from earth at the rate of about 4 inches a year. It is stealing rotational momentum from Earth, and thus the Earth's rotation is slowing. It used to be something like 12 hours a day way back, and the moon was much closer.
It might get further away, but it will still be around when the Sun goes Nova and swallows it all anyhow.
Earth not swallowed by Sun? (Score:2, Interesting)
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.)
Not 12 hours, 25 hours a day (Score:2)
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.
19 Hour Days (Score:2)
Not the Earth! (Score:1)
The Physics & Science of the Moon (Score:1)
We would all be cheesed off.
Thank you. Thank you Very Much.
Two Scientific Errors (Score:1)
Professor D. Martin has predicted the outcome. (Score:1)
That's amore.
At that point you'll sing "Vita Bella".
uhh... duh. (Score:4, Funny)
sheesh. i don't know why questions like this even get posted. The movie only just came out this spring.
Re:uhh... duh. (Score:1)
Oh that'll do them good...
Re:uhh... duh. (Score:1)
Well..... (Score:1)
Thats just a guess though...
the real question... (Score:1)
The Musings of Dave (Score:2)
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?
The Media Angle (Score:2, Funny)
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.
The Question is bassackward (Score:2)
Geesh, how do you expect to get intelligent answers, when you ask the wrong silly question.
RTFM (Reverse the Freaking Moon)
Endor Holocaust (Score:2)