Hi, just a random question but if the Xindi (or anyone really) had blown up Earth, what would have happened to the Moon in the resulting explosion? I guess this question could be done in an other way as if you were on the Moon and the Earth blew up, what would happen to the Moon/you? Cheers for having a look this guys.
Shock waves (real world) don't travel through space. If the Earth were blasted into gravel, but stayed in the same general area, the gravity well created by the mass would still be there, and the moon would continue to orbit it. If the Earth basically disappeared, then the moon would continue to orbit the sun, it's new orbit would be effected by where it was in it's orbit of the Earth when the Earth ceased to exist.
Or then miss. But unless what we see in "Twilight" happens in slow motion, the chunks are moving relatively slowly away from some sort of a remaining glowing core - so slowly that they ought to remain in orbits that will intersect the former location of Earth annually, for centuries to come. So eventually there would be hits. And some of the "Twilight" chunks were almost Moon-sized. Since there would be less mass there to keep the Moon orbiting (perhaps none, if the glowing core also dissipated somehow), the Moon would also start to wander - but again slowly enough that its path would still have high odds of intercepting with those of the pieces of debris. We also have to consider that the Xindi were on a mission to eradicate every last remnant of mankind. They even hunted down their last refuge at Ceti Alpha eventually. So surely they would also take care to destroy the Moon and its human settlements, now that they were there? Timo Saloniemi
It's hard to predict how planets behave when exploding, as thus far we've yet to record one that instantaneously blows up. Planets are fairly sturdy and if presure builds up, they tend to let that out by means of vulcanoes, shifting the tectonic plates or whatever. I think they'd at best crack and gravity would keep those pieces tightly pulled together. But I'm a geek, not a geologist.
The idea of blowing up a planet is a very silly one. It would take an insane amount of energy to disintegrate the Earth, more than the Sun gives off in a week. And it's so unnecessary. You don't need to physically break apart a whole planet to kill its inhabitants, since they only occupy a very thin film of air and water on its surface. Most of it is just inoffensive rock and metal. So it's a total waste of energy to destroy anything deeper than the surface layer -- or maybe a few kilometers beneath it if the civilization you want to destroy has deep underground bunkers or mines they could retreat to. But we're still talking about a layer that's proportionally thinner than the paint on a cue ball. No need to build a planet-shattering megaweapon, just lob a couple of big asteroids at the planet and let them render the surface uninhabitable. Or smash a starship into the planet at half the speed of light. Sci-fi's preoccupation with exotic planet-killer weapons is misguided, when any drive capable of FTL or high sublight speeds is already a potential weapon of planetary-scale mass destruction. Although one can rationalize this by assuming that civilized planets have defenses against asteroids or suicide ships coming in at high velocities, so something that can approach more slowly and then unleash a devastating ray is necessary to get past those defenses. But still, assuming the ray needs enough energy to destroy the entire inert mass of rock and metal rather than just the ultra-thin veneer of life, air, and water on its surface is overthinking the problem enormously.
Christopher, aliens operate on "Rule of Cool" far more than Earthlings do. That's why all the flashy gadgets, 'sploshuns, and improbable energy weapons. The aliens dismissed "Star Wars" and all Roland Emmerich films long ago as mundane ... boring ... too much like real life.
In Space Battleship Yamato, killing a planet started off as just a matter of hitting it with asteroids and large missiles to devastate the Crust and things above it. But things escalated. Wave Motion Weapons, in numbers, were found to be able to rip planets apart even though they were designed as anti-fleet weaponry (it seems to have been a side effect of the power systems used, and not its original design intent). From there super large inter-galactic planet killer missiles were made to increase the distance one could kill an enemy planet. Black Hole weapons were constructed as well. The side effects of these two resulted in star killer weaponry, which was not intentionally used, as most races had need of the stars even if they wanted to vaporize a particular planet. Most of these weapons became the basis for prolonged Inter galactic Cold Wars. Mutually Assured Destruction from Warp powered planet killing missiles to ensure Empires would not attack each other. At least that was the goal. It didn't work as well as suggested.
I was always impressed by the scenes of planet destruction in Star Blazers/Yamato, because it wasn't just an instantaneous "pow" like Star Wars's totally ridiculous portrayal of Alderaan's destruction, but was a slow, turbulent process of the planet turning molten and erupting from within, tearing itself apart gradually like something as huge as a planet would presumably do. Ditto the destruction of the Genesis Planet in The Search for Spock. You could definitely turn a planet molten like that by hitting it with something big and/or fast enough, and that would send a lot of debris flying out into space; but it would go into orbit and eventually settle into a single body, which is how the Moon was probably created. And the rest of the molten planet would still be held together by its own gravity, so it'd just cool back down into a planet again over time. The part where the planet actually blows apart entirely and isn't there anymore is the nonsensical part. If you blow up a car or a building, the debris doesn't fly out into space; it flies up but then falls back down under the planet's gravity. If the entire planet blew up, the same would happen with most of its debris, even if some pieces of it were accelerated past escape velocity. You'd end up with a slightly smaller, molten planet with a debris ring around it; you wouldn't end up with no planet at all.
Maybe the Xindi would blow up the Moon as well? They'd probably be able to detect the human colonies which exist there. So the Moon would be a target just like Earth was. Remember, as "Twilight" showed, the Xindi were on a mission to wipe out the entire species, not just the homeworld...
In Yamato 2199, Yamato destroys a giant power generation system on Balun, which appears to be either a Gas Giant or a Brown Dwarf star. The explosion expands the planet out many time (destroying the ships in orbit). But the planet eventually contracts to more or less the shape is was before. Maybe slightly smaller and with a different cloud pattern. When Yamato returns there some three or more months later, they are shocked by the destruction they caused with one wave motion gun blast. But Balun is still there.
As long as Earth's debris is within the circumference of Lunar orbit, the moon should maintain its orbit. Once the debris starts getting outside Lunar orbit, the gravitational pull at the center of the two body system will decrease for the moon, and its orbit will start growing at an ever faster pace. This assumes the energy put into Earth is enough to cause a permanent mass scattering. If the Earth's debris does not have enough energy to permanently scatter, than the moon should maintain its orbit as it would with the Earth intact. Earth would eventually reform into a planet. In either case, it is likely the moon gets pummeled by huge chunks of ex-Earth. There should be some parts which escape the system, even if the whole cannot.
Remember in TWOK the Enterprise had to out run the shockwave after Kahn detonated the Genesis Device. This is why it is called science fiction and not science fact.
It wasn't so much that they had to get out of the way of a blast zone. They had to get out of the way of the Genesis effect. It took the matter from the Nebula condensed it rapidly into a planet. Outsside of the explosion of the Reliant, they were having to outrace an implosion.
God, I so hate it when people say that. That is not why it's called science fiction. It's called science fiction because it's fiction based on scientific ideas and situations, which can include realistic science or unrealistic science depending on the preference of the storyteller. The same goes for any other genre. Historical fiction is often based on very accurate history, with the fictional parts interpolated between the known facts. Military fiction is often based on accurate and detailed knowledge of military strategy, tactics, hardware, culture, and the like. And so on. Fictional means unreal, but that's not automatically the same as unrealistic. There is a whole, large, expansive genre of science fiction, known as hard science fiction, which is specifically about basing stories on the most realistic and plausible science the writers can manage. This type of science fiction has been a part of the genre since the days of Jules Verne. It's the type of science fiction I write myself. Please don't casually dismiss its very existence.
The effect of the original Xindi probe in "The Expanse" was much more believable, as it seemed designed to sterilise the surface rather than actually explode the planet.
Cheers guys. I was reading the article on Memory Alpha about the Xindi destroying Earth and when wondering if the Moon would be the next target I began to wonder if there'd be any need for it if it'd already been destroyed in the same blast (I can never get a handle on how big space really is). I love sci-fi superweapons like the Xindi weapon and Death Stars. It was pretty great when Babylon 5 busted out a couple of different planet killers in season 4.
Or then it just finally hit its intended target, the nearest planet (namely, the D class rock Regula), and did its magic with that one. The nebula appeared to be gone in an eyeblink (when the Reliant explodes, it's no longer there, it apparently being too much of a VFX hassle to include it in the shot). But having expanding spheres of whatnot in space is perfectly realistic. Calling them "shockwaves" might be taking liberties with the term, as there may well be shock involved, but the sphere isn't doing any sort of wave motion in- or outside a medium. But just having them is fine and well, especially if they move at any speed below c. In Star Trek, speeds above c are also allowed, of course. As for blowing up planets, it may well be a case of the advanced and powerful aliens not bothering to downscale their doomsday weapon for this special application. An M60 machine gun might be excessive for killing a wolf, but if that's the thing you are carrying when the shepherd comes asking for a way to deal with the beast, there you have it. It's not as if the Xindi designed or even truly built this weapon. They just acted as the physical hands of the real makers, who supposedly already were well beyond blowing up mere planets. Timo Saloniemi