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This picture got me thinking, whether such collision would be possible, and would it really look like that from the moon.

What would be the properties (mass, size, velocity etc.) of an object, whose collision with Earth would completely destroy it in the manner of that picture? That is, after the collision, a large portion (if not most) of Earth would continue straight along the same path as that of the colliding object, but from the opposite side of the planet.

If such an event were to happen, would the sight in that picture be an accurate depiction when observed from the surface of the moon?

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  • $\begingroup$ This is dangerously close to the counterfactual parts of science fiction. $\endgroup$ – Emilio Pisanty Mar 21 '14 at 13:25
  • $\begingroup$ The earth is quite a bit smaller in reality as compared to that image. $\endgroup$ – Kyle Kanos Mar 21 '14 at 13:25
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    $\begingroup$ @Kyle Kanos: Ī hope you have some notion of geometric perspective in the circumlunar space ☺ A flat, rectangular image of a 3D scene does not always contain hints about angular sizes of objects. To know how to translate millimetres or pixels to degrees one must know the ratio of focal length to physical dimensions of the original image; neither is usually evident… $\endgroup$ – Incnis Mrsi Oct 19 '14 at 17:58
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    $\begingroup$ But on this picture we have Earth with its known size, and roughly know the distance to it. Does visible dimensions of the astronaut contradict to diameter of the Earth (might be about 2°)? They do not, because he is imagined slightly from above, from an unknown height. What you perceive as “the Earth is quite a bit smaller in reality” actually means “Kyle Kanos is not accustomed to narrow-angle photographs” (that is predictable: cameras used in Apollo’s lunar excursions were wide-angle ones) “and is short of imagination”. But does anybody claim it is an Apollo expedition? $\endgroup$ – Incnis Mrsi Oct 19 '14 at 18:03
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    $\begingroup$ A single proton with high enough velocity would suffice. There was an answer recently either here or on Worldbuilding covering this, but I can't find it right now. $\endgroup$ – Jim Garrison Mar 11 '16 at 6:33
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Earth is really, really big (in comparison to that projectile). In order for an object to completely penetrate it, it would need to have enough force to go through 12,742 kilometers of solid and liquid. It would need either extreme mass or extreme speed.

in the case of extreme mass, at a certain point, the object wouldn't go straight through earth as much as tear it apart from a distance due to gravitational forces and the roche limit. This happens at the approach side, not at the exit side.

In the case of extreme speed, at a certain point, an object would be so fast that the collision turns the object and a large part of earth into plasma. The object itself would not survive as shown in the image, unless it's also extremely resistant to the massive forces involved in this event.

So an object which would be capable of this would need to be both extremely massive and extremely fast. As luck would have it, Randall Munroe actually made an educated guess on the consequences of a 100 meter wide diamond meteor striking earth at relativistic speeds. His conclusion was that the meteor would have an effect far worse than that of the image above. The entire planet would desintegrate into a massive cloud of plasma, which would destroy most of the moon as well, sweep away most of Mars and Venus and have a sizeable effect on the Sun.

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  • $\begingroup$ “0.9999999999999999999999951c” is not plainly “relativistic”, but ultra relativistic. $\endgroup$ – Incnis Mrsi Aug 23 '14 at 11:35
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IMHO a dust-particle-sized black hole, roughly of the mass of Pluto, moving at few hundreds km/s, could produce effects similar to those are pictured, namely:

  • Ejecta above the entry point (destruction of the crust by the hole’s gravity);
  • Except vicinity of aforementioned point, an almost undamaged leading hemisphere (tidal forces become too weak to break the crust severely, whereas too few time elapsed for sound waves to propagate across the planet);
  • Grave damage and incandescent plume at the tailing hemisphere (the hole, on its descent, should drag a significant part of the Earth’s interior that will then penetrate the mantle and core at supersonic speeds, generating shock waves);
  • A cloud of plasma around the object (for few seconds, or maybe less, the hole should hold a globular cloud of matter around it, before it partially dissipates to outer space, partially falls inside, and possibly transforms to accretion disc).

It really should appear “out of nowhere”, as the explanatory text says (note to @miikkas: Ī changed the URL since the one at memecdn.com now gives 404). Modern Solar System astronomy does not deploy instruments to detect such objects purposely, whereas without impacts it will be completely black to human eye and telescopes.

Black holes of smaller masses, moreover, will be virtually traceless because probability to significantly perturb a noticeable body will be minor.

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