How to destroy the Earth

[DFINITLYDISTRUBD]

D.D.-Load a TBM with nukes and other assorted weapons of mass destruction... aim it for the earths core...start it up and wait.:hihi:

les see will it or won't it?

[CraigD]

D.D.-Load a TBM with nukes and other assorted weapons of mass destruction... aim it for the earths core...start it up and wait.:hihi:

les see will it or won't it?

Short answer: it won’t.

 

From this post on the subject of heating mars with nuclear explosives, we can make a very high estimate that the total energy of all the nukes ever made total about [math]5 \times 10^{21} \,\mbox{J}[/math]. A couple of independent estimates of the energy necessary to actually blow up the Earth – send all its pieces going their separate ways – come up with a figure of about [math]2 \times 10^{32} \,\mbox{J}[/math]. So, all the world’s Nukes have about one 40-billionth of the energy needed.

 

Without working out the details, I’ve a hunch that detonating all the nukes in the world at the Earth’s core wouldn’t even be a significant seismological event.

 

Then there’s the question of making a tunnel boring machine that can get anywhere near the Earth’s core. Though the subject of some fun science fiction going back to at least 1864, the reality is that no such technology is even close to existing. Even if such a machine could be built, once it penetrated the crust, it would need to be a magma-swimming machine, then an iron-boring machine – pretty extreme engineering challenges.

 

This is pretty much the point of this thread – destroying the Earth would be much, much more difficult than is commonly believed.

[Turtle]

I listened to a fella, Phil Plait I think, on the radio last week, and the subject of the Sun burning out came up and so then what could we Earthians do. The plan he put forward is to capture a sizeable asteroid (sizeable? :):doh:) and put it in orbit around Earth in such a manner that it tugs Earth slowly into a larger orbit. I want to rmember the guy said he saw practical calculations for this. :hihi: (Craig!? :doh:)

 

So, to destroy Earth, we do the same thing except use an orbit for the asteroid that pushes Earth into the Sun. Bada bing; badda bang boom. :)

 

BBC News | SCI/TECH | Planet Earth on the move

...Using the well-understood "gravitational sling shot" technique that has been employed to send space probes to the outer planets, the researchers now think a large asteroid could be used to reposition the Earth to maintain a benign global climate.

 

It is an "alarmingly simple" technique, the astronomers say. It could ensure humanity's survival and even allow our descendants to alter our Solar System to move moons and planets to make new Earths.

 

The astonishing idea has been put forward by Don Korycansky, of the University of California, along with Gregory Laughlin, of the US space Agency Nasa, and Fred Adams, of the University of Michigan. ...

[CraigD]

I listened to a fella, Phil Plait I think, on the radio last week, and the subject of the Sun burning out came up and so then what could we Earthians do. The plan he put forward is to capture a sizeable asteroid (sizeable? :shrug::doh:) and put it in orbit around Earth in such a manner that it tugs Earth slowly into a larger orbit. I want to rmember the guy said he saw practical calculations for this. :confused: (Craig!? :hyper:)

The “gravity tug” idea is a major one in the young engineering discipline of altering the orbits of celestial bodies. Mostly, it’s been proposed as a way that a dangerously large NEO found to be on a collision course with Earth could diverted enough to avert disaster. It’s attractive because it solves the problem of how to “get a grip” or “find a hard point” on an such an asteroid, which observation suggest are more “gravel balls” than solid objects one could just bolt rocket motors onto.

 

The approach applies well to moving Earth, too, as it “spreads the load” of the required thrust more smoothly than rigid structures (Earth surface-mounted rockets, deeply-anchored cables into space, etc), at worst playing hell with tides and weather, but not threatening to cause earthquakes or collapse of big pieces of the surface, while keeping any motors well clear and out of the atmosphere.

 

It doesn’t get around the need for a lot of energy, though, as something has to give the tugging asteroid/moon acceleration. Simply put into orbit around Earth, such a body, no matter how large, would accelerate it an equal amount in all directions along its orbital plane, for a net acceleration of zero. “A lot of energy” here means a LOT of energy – about [math]2.2 \times 10^{33} \,\mbox{J}[/math], roughly ten time the amount required to explosively disintegrate the whole Earth. Super space engineering, again.

 

Super space engineering though it may be, if you’re willing to take very long time to do it, it’s not inconceivable. In Turtle’s linked-to article , NASA’s Gregory Laughlin’s scheme to move the Earth to an orbit large enough that a 10% increase in solar energy output continues to give Earth the same energy input (increasing its orbital radius from 1 AU to 1.004881 AU) involves a tug from a 100 km asteroid every 6,000 years, presumable repeated about 200 million times over a period of about a billion years. This is super space engineering on a very long timeline!

 

If you work out the transfer orbit requirements of the 1 AU – to 1.004881 AU transfer (which includes a the nudges needed on the “top end” to re-circularize Earth’s orbit, you get a total of about 700.25 m/s delta-v, vs. 26877 for a 1-way transfer orbit into the surface of the Sun (at about .0047 AU), requiring a “mere” .00068 times the energy – a tiny fraction of the Earth-shattering energies we’ve been discussing).

 

If you have the technology to do it with one big asteroid ever 6,000 years, however, there’s nothing in principle stopping you from doing it with more and bigger asteroids more frequently.

 

The big picture in such a scheme, either the moving Earth out a little or moving it in all the way one, is to get a “conveyor belt” of bodies, the more and the more massive the better, moving on closed orbits between Earth and some other large body (the largest, Jupiter, is an obvious candidate), transferring momentum between the large bodies by transferring it between the small ones and the large ones. Super space engineering, the high-level executive summary kind.

 

The main constraint on how fast such a scheme could alter the Earth’s orbit is the amount of mass – lots of asteroids, etc. – you can get on the “conveyor”, and how efficiently you can engineer their orbits to make close passes at the large bodies. There are so many variable in this I can’t begin to make any estimates, but my guess is that even the super-est space engineers couldn’t manage any major orbit changes in less than thousands of years.

 

Somehow, this lacks the space-opera dramatic zing of a Star-Wars type death-star – it’s hard to promote a “policy of fear” with statements like “Impudent Earthlings! Prepare to meet your ends … in 150,000 years!”

[freeztar]

Great post Craig. It reminded me of this article I read years ago.

SPACE.com -- Recipe for Saving Earth: Move It

[Moontanman]

PS: Post #1’s link to Sam Huge’s “how to destroy the Earth” webpage is broken. Here’s its 3/2/2005 archive, and its latest (7/11/2007) one.Huge and the several hypographer’s over several years appear to me right on the subject – literally blasting the Earth into never-to-reform rubble would NOT be easy.

 

By my very rough model, the total gravitational potential energy of the Earth (that is, how much GPE was lost by all of its little pieces when the fell together to form it) is about [math]1.8 times 10^{32} ,mbox{J}[/math] (not too far from UncleAl’s wikipedia figure of [math]1.8 times 10^{32} ,mbox{J}[/math], so my model appears not too rough after all ;)). This is a lot of energy – about 5.4 days of the Sun’s total energy output. Assuming, then, that the Earth is held together by nothing more than gravity (not, I think, an unreasonable assumption, for estimating purposes), and that you could somehow perfectly apply the energy to exploding it, you’d need to use a minimum of that much energy to completely take it apart. Per my model again, it doesn’t much matter what size rubble – reducing it to tiny pieces takes only slightly more energy than reducing it to moon-size chunks.

 

I can only imagine a few ways to accomplishing this:

• A giant impactor
  
• An antimatter bomb
  
• A small, ultra dense (black hole-ish) object
  

Giant impactor approach

[math]1.8 times 10^{32} ,mbox{J} dot = frac{1}{2} 0.0026 ,mbox{M}_{mbox{E}} (150000 mbox{m/s})^2[/math], so a body around the mass and initial position of Pluto, nudged to fall inward, then be deflected into a retrograde orbit that exactly strikes Earth, would be just about the minimum necessary.

 

Getting all of an impactor’s kinetic energy to accelerate each bit of Earth equally seems undoable – some pieces would almost certainly get much more, other much less, so what would result from this would likely be a debris cloud a significant fraction of Earth’s original mass that would eventually recoalesce into a smaller planet/ring/moon system (likely in very interesting ways). You might even just “punch a hole” in the Earth, and wind up with no worse than a topsy-turvy jumbled-up reconfigured Earth with nothing worse than “capsized tectonic places, a century or two or planetary rings and constant meteorite showers, a new moon or two, etc. Though not a total disintegration, I’d say any of these scenarios still qualifies, or come pretty close to qualifying, as “destroying the Earth”.

 

Getting a [math]1.6 times 10^{22} ,mbox{kg}[/math] Kuiper belt object to hit the Earth would be a colossal, though not IMHO inconceivable, project. You’d likely have to directly force small bodies (using a spacecraft-based approach like that being considered by groups such as the B612 Foundation, use these to alter the orbit of larger ones, etc., until you can put one of the largest KBO onto a that takes it into just the right grazing path with one or more giant planets to accomplish the final, weird change to a retrograde Earth collision orbit.

 

Antimatter bomb approach

[math]1.8 times 10^{32} ,mbox{J} / c^2 dot= 2 times 10^{15} ,mbox{kg}[/math], so half this mass of antimatter annihilating with matter meets the minimum-to-disintegrate the Earth threshold. [math]10^{15} ,mbox{kg}[/math] is a lot, but not astronomically – about 167,000 Great Pyramids, all the practical coal reserves on Earth, 40 Iceberg B-12s, or a 12 km diameter sphere of water.

 

Since there’s essentially no naturally occurring antimatter, this would have to be manufactured. Taking the most optimistic estimated for anti-matter factory efficiency (about 0.01%), to manufacture this much antimatter, you’d need about 2 years of the Sun’s total power. To get anything like this, you’ve got to do space solar power engineering on a scale requiring the dismantling of at least major asteroid-size bodies, put them in the closest possible solar orbit, build giant factories in space, etc.

 

Anybody who could do this could think of much more effective ways of messing with the Earth than blowing it up. ;)

 

Black hole-ish approach

Celebrated in several works of science fiction (notably James Hogans 1980 “Thrice Upon A Time” Greg Bear’s 1987 “The Forge of God”), this approach requires some super-material engineering technology, with which you somehow make an very dense object, and drop it into the Earth. Due to friction, its subterranean orbit should quickly become nearly stationary at the Earth’s core, where it will begin stripping matter from the less dense core and behaving like a neutron star, gaining degenerate matter and radiating x-ray and more energetic radiation. Depending on complicated factors, something awful – the Earth becoming a tiny neutron star – will happen sooner or later.

 

This isn’t a true disintegration – Earth likely won’t lose much mass – but it renders the Earth entirely inhospitable to present-day human life, so I’d say qualifies as “destroying the Earth”.

 

In short, with any of these approaches, we’re talking super science and engineering, likely (at least for the giant impactor approach) centuries of it. This isn’t accomplishable today, or likely in a human generation. Given the resources it would take to do such a thing, it’d likely require the cooperation of all of humankind, which, for a “destroy the Earth” project, seems very unlikely.

 

PS: Post #2’s and Huge’s “direct the Earth into the sun” approach requires about 10 time the energy of a direct “explode it” approach. The Hohmann transfer orbit for 1 AU ([math]1.5 times 10^{11} ,mbox{m}[/math]) to grazing the Sun’s surface ([math]7 times 10^{8} ,mbox{m}[/math] requires an initial speed change of about 26877 m/s, a [math]2.2 times 10^{33} ,mbox{J}[/math] kinetic energy change.

 

The forge of God approch was to drob two chunks of nuetronium into the earth both were around basket ball sized, one was matter the other was antimatter. After they orbited around inside the earth for a while they would come together and boom the earth is blasted away! No black hole was nesesarry. but then again i don't think we have that tecnology yet. As for striking the earth with another object, an asteroid impact of about 300 miles in diameter is enouth energy to melt the earth's crust down to a depth of a couple of miles or so. The planet would survive but it wouldn't be the earth we know! The earth survived an impact from a mars sized planet early in it'

s history (suposedly) and the result was the moon. I'm not sure if we will ever have the energy to destroy the earth in one bang but you could change it's orbit drastically by passing numerous asteroids by the earth over thosands of years. I guess if you did it corectly you could eventually cause the earth to hit the sun or jupiter.

 

michael

[alexander]

Those movies were both about a fight for humanity, not the Earth.

machines fight humans, humans want to destroy machines, so they logically build the biggest bomb, and bam, world gone :hihi:

As As Craig discussed several posts back, an impactor around the size of Pluto would be the minimum necessary and the tech neeeded to pull it off is not likely to come about for quite some time, if ever.

Let's investigate that a bit, i would think this is dependent on what the makeup of the object is, and how fast it's traveling... also what you mean by total eniolation? so that every bit of earth matter is destroyed, or so that it is just unearthed?

 

Back to comet approach...

 

This i can recall from some stuff i have read, when we observed Shoemaker-Levy 9 visit Jupiter. The fragments were no larger then 2km in size, traveling at 60km/s.

 

The nucleus bit hit jupiter first, as i can recall. The fire ball reached 24,000K, the plume reached 3000km in height. Debris occupied an area the diameter of earth.

 

Just researched it a little more, and here is the interesting bit, the largest piece (about 2km in diameter) left debris in an area about 12000km in size, and generated an approximate force of 6,000,000 megatons.

 

Hit from the right side of earth, of that proportion, will set earth off it's orbit and possibly push it towards the sun, where sun's gravity will take over and eventualy the planet is swallowed by the star and tada, earth destroyed... ?

 

But trust me, i have other thoughts on this too, i was just talking giant impact approach.... it's not like Pluto will be able to make it all the way to earth before it mostly melts, k...?

 

1) Ok, Call this project "The Laser". We take a giant curved reflective surface (giant mirror) and place it in rotation with earth, though keeping it's angle constant to the sun. the giant miror will reflect sun light and concentrate it on one area of the planet that will generate energy pushing the planet towards the sun, and eventually eniolating earth.

 

2) We can use one of professor Fonzworth's doom's day devices (futurama reference)

 

3) A(tomic)S(trong)N(uclear)P(ulse) device (one that will disable the flow of strong nuclear energy that holds atoms together) (bam and world is gone :) )

 

4) Parallel universe collision :hihi:

[DFINITLYDISTRUBD]

Short answer: it won’t.

 

From this post on the subject of heating mars with nuclear explosives, we can make a very high estimate that the total energy of all the nukes ever made total about [math]5 times 10^{21} ,mbox{J}[/math]. A couple of independent estimates of the energy necessary to actually blow up the Earth – send all its pieces going their separate ways – come up with a figure of about [math]2 times 10^{32} ,mbox{J}[/math]. So, all the world’s Nukes have about one 40-billionth of the energy needed.

 

Without working out the details, I’ve a hunch that detonating all the nukes in the world at the Earth’s core wouldn’t even be a significant seismological event.

 

Then there’s the question of making a tunnel boring machine that can get anywhere near the Earth’s core. Though the subject of some fun science fiction going back to at least 1864, the reality is that no such technology is even close to existing. Even if such a machine could be built, once it penetrated the crust, it would need to be a magma-swimming machine, then an iron-boring machine – pretty extreme engineering challenges.

 

This is pretty much the point of this thread – destroying the Earth would be much, much more difficult than is commonly believed.

 

Don't hate me...you put alotta work into this responce....but....

les see will it or won't it?

was actually refering too whether or not my repost would actually land in the propper thread rather this time. Last time it went to the thread I was looking at before this one- "200,000th post". (aparently it might be dangerous to change my tuneskeys whilst posting...at least that's the best I can figure as to the cause.)

 

Though I have to admit that I hadn't given the whole magma part of the equation much thought. Good point...I think tungsten or berylium would hold

up to the heat....maybe?!?!?!?!?

[Turtle]

...

Super space engineering though it may be, if you’re willing to take very long time to do it, it’s not inconceivable. In Turtle’s linked-to article , NASA’s Gregory Laughlin’s scheme to move the Earth to an orbit large enough that a 10% increase in solar energy output continues to give Earth the same energy input (increasing its orbital radius from 1 AU to 1.004881 AU) involves a tug from a 100 km asteroid every 6,000 years, presumably repeated about 200 million times over a period of about a billion years. This is super space engineering on a very long timeline!

 

So we have a demonstrable method using a captured asteroid, (Craig's clever addition notwithstanding) to propel the Earth to destruction in the Sun. If we go with the 'once-every-6,000-year schedule, then it is possible that such an asteroid is in orbit and we simply haven't found it yet. :hihi:

 

If this is the case, would we recognize that an asteroid was artificially, that is by intelligent means in the past, placed into a gravity tugging orbit of Earth? In line with the Physics of God thread, I find it a fascinating theme for some science fiction. :hihi:

[CraigD]

As As Craig discussed several posts back, an impactor around the size of Pluto would be the minimum necessary and the tech neeeded to pull it off is not likely to come about for quite some time, if ever.

Let's investigate that a bit, i would think this is dependent on what the makeup of the object is, and how fast it's traveling... also what you mean by total eniolation? so that every bit of earth matter is destroyed, or so that it is just unearthed?

Here’re the technical underpinnings of the results I came up with in post #27.

By my very rough model, the total gravitational potential energy of the Earth (that is, how much GPE was lost by all of its little pieces when the fell together to form it) is about [math]1.8 times 10^{32} ,mbox{J}[/math]

My “very rough model” was to calculate the gravitational potential energy of 2 small spherical bodies at a large (effectively infinite) distance, minus their energy when they are adjacent to one another. This is the energy necessary to separate them from one another at their mutual escape velocities, so (ignoring the rest of the universe) that they never fall together again. I then assume the two bodies merge into a single spherical body, and repeat the calculation for two spheres with that mass, and so on, until I get a mass equal to the Earth’s, keeping a running total of the energy. The value, about 1.727e32 J, was close to the 2.24e32 J I read in post #5’s reference to the wikipedia article “Gravitational binding energy”, so I congratulated myself and moved on. Here’s the actual MUMPS program:

s G=6.67e-11,D=5500,M=1.24,E=0 f C=0:1 s r=M/D*3/4/**(1/3) s R=M x XSN w (C,2)," ",R," " s R=r x XSN w R," " s R=E x XSN w R,! r R s E=G*M*M/2/r*2+E,M=M+M

and its actual output (iteration mass radius energy)

 0 1.240e0 3.776e-2 0.000e0
1 2.480e0 4.757e-2 2.716e-9
2 4.960e0 5.993e-2 1.134e-8
3 9.920e0 7.551e-2 3.872e-8
4 1.984e1 9.514e-2 1.256e-7
5 3.968e1 1.199e-1 4.016e-7
6 7.936e1 1.510e-1 1.278e-6
7 1.587e2 1.903e-1 4.059e-6
8 3.174e2 2.397e-1 1.289e-5
9 6.349e2 3.021e-1 4.093e-5
10 1.270e3 3.806e-1 1.299e-4
11 2.540e3 4.795e-1 4.125e-4
12 5.079e3 6.041e-1 1.310e-3
13 1.016e4 7.611e-1 4.158e-3
14 2.032e4 9.590e-1 1.320e-2
15 4.063e4 1.208e0 4.191e-2
16 8.126e4 1.522e0 1.331e-1
17 1.625e5 1.918e0 4.224e-1
18 3.251e5 2.416e0 1.341e0
19 6.501e5 3.044e0 4.258e0
20 1.300e6 3.836e0 1.352e1
21 2.600e6 4.833e0 4.292e1
22 5.201e6 6.089e0 1.362e2
23 1.040e7 7.672e0 4.326e2
24 2.080e7 9.666e0 1.373e3
25 4.161e7 1.218e1 4.360e3
26 8.321e7 1.534e1 1.384e4
27 1.664e8 1.933e1 4.394e4
28 3.329e8 2.436e1 1.395e5
29 6.657e8 3.069e1 4.429e5
30 1.331e9 3.866e1 1.406e6
31 2.663e9 4.871e1 4.465e6
32 5.326e9 6.137e1 1.417e7
33 1.065e10 7.733e1 4.500e7
34 2.130e10 9.742e1 1.429e8
35 4.261e10 1.227e2 4.536e8
36 8.521e10 1.547e2 1.440e9
37 1.704e11 1.948e2 4.572e9
38 3.408e11 2.455e2 1.451e10
39 6.817e11 3.093e2 4.608e10
40 1.363e12 3.897e2 1.463e11
41 2.727e12 4.910e2 4.645e11
42 5.454e12 6.186e2 1.475e12
43 1.091e13 7.794e2 4.681e12
44 2.181e13 9.820e2 1.486e13
45 4.363e13 1.237e3 4.719e13
46 8.726e13 1.559e3 1.498e14
47 1.745e14 1.964e3 4.756e14
48 3.490e14 2.474e3 1.510e15
49 6.981e14 3.118e3 4.794e15
50 1.396e15 3.928e3 1.522e16
51 2.792e15 4.949e3 4.832e16
52 5.584e15 6.235e3 1.534e17
53 1.117e16 7.856e3 4.870e17
54 2.234e16 9.898e3 1.546e18
55 4.468e16 1.247e4 4.909e18
56 8.935e16 1.571e4 1.558e19
57 1.787e17 1.980e4 4.948e19
58 3.574e17 2.494e4 1.571e20
59 7.148e17 3.142e4 4.987e20
60 1.430e18 3.959e4 1.583e21
61 2.859e18 4.988e4 5.027e21
62 5.718e18 6.285e4 1.596e22
63 1.144e19 7.918e4 5.067e22
64 2.287e19 9.976e4 1.609e23
65 4.575e19 1.257e5 5.107e23
66 9.150e19 1.584e5 1.621e24
67 1.830e20 1.995e5 5.147e24
68 3.660e20 2.514e5 1.634e25
69 7.320e20 3.167e5 5.188e25
70 1.464e21 3.990e5 1.647e26
71 2.928e21 5.028e5 5.229e26
72 5.856e21 6.334e5 1.660e27
73 1.171e22 7.981e5 5.271e27
74 2.342e22 1.006e6 1.673e28
75 4.685e22 1.267e6 5.313e28
76 9.369e22 1.596e6 1.687e29
77 1.874e23 2.011e6 5.355e29
78 3.748e23 2.534e6 1.700e30
79 7.495e23 3.192e6 5.397e30
80 1.499e24 4.022e6 1.714e31
81 2.998e24 5.068e6 5.440e31
82 5.996e24 6.385e6 1.727e32

An interesting observation from this is it doesn’t take much more energy to break the earth into many, many sub-kilogram mass pieces than it does to break it into only about a million moon-size pieces, or 8 Mars-size pieces.

 

My program’s actually wrong – it should double the energy with each iteration, resulting in a value (from a corrected version) of 3.197e32 J, but a mere difference of a factor of two isn’t very significant for this sort of estimation, so I mention the corrected version only as an afterthought.

 

[math]1.8 times 10^{32} ,mbox{J} dot = frac{1}{2} 0.0026 ,mbox{M}_{mbox{E}} (150000 mbox{m/s})^2[/math], so a body around the mass and initial position of Pluto, nudged to fall inward, then be deflected into a retrograde orbit that exactly strikes Earth, would be just about the minimum necessary.

The mystery term here is the 150000 m/s impact speed. I got that by taking the speed that a body freefalling from an infinite distance to 1 AU (about [math]\sqrt{\frac{2 G M}{r}} = 42119 \,\mbox{m/s}[/math]), and adding that to Earth’s orbital velocity of about 107218 m/s. Recall that the scenario I describe has our super-orbital engineers getting Pluto to “cross up” into a retrograde orbit trajectory and smack Earth head on.

 

As for what the impactor’s made of, from an energy perspective, it doesn’t matter. All that matter’s is its mass and velocity. I’m assuming that our super-engineers know just how to break the impactor into the right “shot pattern” that all of its energy gets absorbed by the earth, and directed outward. It’s a valid assumption, I think (though I haven’t, and don’t plan to try to work out a detailed validation), that no matter what ordinary material it’s made of, it’ll be a hot gas/plasma by the time it get to the serious business of Earth-shattering.

 

In reality, this last bit would be a terribly hard bit of engineering. A more likely outcome would be the impactor driving a hole thought Earth’s “fluffy” outer layers, knocking it’s core in as a semi-intact hunk of iron out the other side, or some similar, complicated scenario short of a neat reduction into uniform little proto-planet pieces spreading forever through the universe. If the impactor is something like a star (as in the Earth-into-the-Sun scenario) or a gas giant planet of course just enough to miss with its core, the Earth might just punch through it more or less intact, gaining only a small fraction of the impactor’s kinetic energy.

[Turtle]

... If the impactor is something like a star (as in the Earth-into-the-Sun scenario) or a gas giant planet of course just enough to miss with its core, the Earth might just punch through it more or less intact, gaining only a small fraction of the impactor’s kinetic energy.

 

:eek: I take it with the Earth-into-Sun scenario, it doesn't matter which you call the impactor and which the impactee? Whatever that case, you really think Earth would punch through the Sun without destruction as Buffy requires? :doh:

[CraigD]

:eek: I take it with the Earth-into-Sun scenario, it doesn't matter which you call the impactor and which the impactee? Whatever that case, you really think Earth would punch through the Sun without destruction as Buffy requires?

That’s a hard question. I can’t readily put numbers to it, but I can imagine a likely scenario where yes, the Earth could bore through the Sun with little neither losing nor gaining significant mass, or having their mass dramatically rearranged (the Earth’s that is – the Sun’s mass is pretty much in a continuous state of being dramatically rearranged).

 

Observatories like SOHO have captured dozens of images of comets totally evaporating from close passes with the Sun, but a comet is a very different body than a planet, and particularly different from the planet Earth. A major difference – perhaps the key difference in a collision with the Sun scenario – is that while comets have practically none, Earth has a substantial magnetic field, which produces its magnetosphere, which effectively prevents the very tenuous “extended atmosphere” of the Sun, the solar wind, from striking and interacting with the Earths atmosphere or surface. The Sun is composed almost entirely of plasma, so its individual mater particles are all only weakly connected to one another, charged, and subject to deflection by a magnetic field.

 

The hard question is what would happen then you increase the incoming ion flux a quadrillion-fold from its usual value of about [math]10^{-20} \,\mbox{kg/m}^3[/math] to the [math]10^{-5} \,\mbox{kg/m}^3[/math] of the Sun’s outer layers and the even denser ones beneath. Would Earth’s magnetosphere be squashed into insignificance? Strengthened dramatically by the huge increase in current due to the greater ion flux? Or would something even more exotic happen, such as it channeling hot plasma into one of the poles to rapidly burn a hole completely through the Earth via a “Northern Lights on super-steroids” effect?

 

This question exceeds my modest scientific modeling abilities.

 

An Earth impact with the gassy part of a gas giant is simpler, because the gas giant isn’t plasma, and should transfer momentum and energy to the impacting Earth aerodynamically, in basically the same way as any high-speed body in a gas. It’s still a daunting event to attempt to model, but lacks the weirdness of plasma-magnetic field interaction.

 

In either case, a dead-on, core-to-core impact would, I’m confident, utterly obliterate the Earth, as the Sun’s and gas giants’ cores have densities similar to Earth’s. Using best guess estimates of mass and composition, an Earth-Jupiter collision at a speed above a quite reasonable 130000 m/s (about 125% Earth’s usual orbital speed) might destroy Jupiter’s core, with an estimated total binding energy of about [math]5 \times 10^{25} \,\mbox{J}[/math]. What would become of the remaining 85 to 95% of its mass, its 90% hydrogen atmosphere, is another interesting question.