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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 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.
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.
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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