"That's it! EVERYONE DIES!"
Planetary-scale Physical Annihilation. There used to be a planet here. There isn't anymore; it's gone
See Also: Earth-Shattering Kaboom
, Planet Eater
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- Various incarnations of The Hitchhiker's Guide to the Galaxy do this to Earth from the Vogons, ostensibly because of a hyperspacial express route, though it's really because Earth has the Ultimate Question being calculated, and that would be terrible for all the psychoanalysts. In the novel Mostly Harmless, the Vogons finally succeed in destroying not just Earth, but every version of Earth across all the infinite parallel realities. Douglas Adams was in a very bad mood when he wrote that one.
- Superman's backstory is his planet Krypton exploding spectacularly, becoming the Last (or close enough) Son of Kypton. Occasionally, the planet's sun is what goes, which would push those versions into Class X-2, but the majority just had the planet explode. As of Infinite Crisis, Krypton's sun Rao still exists in the comics, but the entire planet was blown to smithereens, presumably naturally.
- Transformers has had Unicron eat a planet or two.
Anime and Manga
- Earth and (eventually) Namek in Dragon Ball Z. Earth was reset with the Dragon Balls, and part of Namek's population was resurrected and given a new home. Arlia was less lucky.
- Earth actually gets it twice, first from Super Buu, then again in GT thanks to the effects of the Black Star Dragon Balls. The Namekian Dragon Balls restored it both times.
- Planet Vegeta gets it before either of them, courtesy of Frieza himself.
- And Frieza has a move called "Destroy the Planet."
- Broly does this countless times. Ironically, he survived Frieza blowing up his planet.
- Majin Buu does this so many times.
- Futari Wa Pretty Cure Splash Star, though it was reversed.
- In Robotech: The Shadow Chronicles, humans nearly blasted Earth, averted only by Invid Regess destroying the missiles. Though they were aiming for Class 2-3 just to get rid of the Invid, but underestimated the power of the Neutron-S missiles.
- In Infinite Ryvius, the Blue Impulse uses gravity manipulation to shatter Saturn's moon Hyperion, killing everyone on it. All six Vaia Ships working in unison would have enough power to alter the ecliptic plane of the entire solar system, which could potentially cause a Class X-2, although they were actually designed to use this ability to prevent a Class X-2.
- Eureka Seven has a phenomenon known as the Limit of Questions. If there are too many intelligent life forms, a black hole or something will destroy the planet. Specifically, the Limit of Questions means that too much sapient life occupying a certain amount of space will create a rift that destroys damn near everything close by, like, say, the planet said life is on.
- Attempted in Diebuster, using Earth as a projectile at significant fractions of the speed of light. The attempt is stopped by Nono/Buster Machine 7 as the Diebuster
- RahXephon. Temporarily.
- Sailor Galaxia is seen casually destroying planets in Sailor Moon StarS way early on in the series.
- She's also seen doing it in her backstory in the manga. And that was before meeting Chaos.
- The Dimension Eater in Macross Frontier. The one we saw took a very large (like a quarter of the planet) out of Gallia IV. A couple more would probably finish the job completely.
- The Protodeviln Gigil annihilates roughly half a planet's mass when he dies in Macross7. The rest of the planet quickly breaks apart due to strain immediately after.
- The titular Hellstar Remina devours the Earth whole.
- This nearly happened in Kill la Kill courtesy of the Life Fibers, which can form a cocoon in the sky over the planet, then breed while absorbing the planet's energy until it blows up and spreads the Fibers through space, in search of new worlds.
- Too many Marvel and DC Comics plotlines to count.
- Narrowly averted in a Donald Duck story about the Universal Solvent, which dissolves everything except diamonds and does not dissipate. When it's poured to the ground, it's going to keep dissolving the planet from within unless the heroes recapture it with a diamond-linen container.
- Star Wars: The Death Star has the power to destroy entire planets, and in A New Hope, it is used on Alderaan, Leia's home planet.
- In Star Trek III: The Search for Spock, the unstable Genesis planet falls apart. Special mention is however reserved for the Genesis Device in Star Trek II, given that it formed a planet from a nebula, which would make it a Class negative X. Or the Class X equivalent if you happen to be a Nebula being.
- In Star Trek VI, the Klingon moon Praxis blows up.
- And now appearing again in 2009's Star Trek film, this time Vulcan, by being sucked into a Black Hole.
- The British 1961 film The Day The Earth Caught Fire has the Earth hurtling towards the Sun when it's thrown out of orbit by a series of large nuclear tests at both poles.
- Arguably, Metaluna's fate in This Island Earth; it's hard to say it's really there if it's now a burning radioactive 'sun'.
- The much larger planet Melancholia smashes into Earth and apparently absorbs all of its mass.
- When Worlds Collide: A star is on a collision course with Earth. Since the end is inevitable, the story concentrates on how to save a handful of lives.
- The Cthulhu Mythos has Dholes, enormous worms that destroy planets by burrowing through them until they collapse. In the Tabletop RPG based on the books, an investigator unfortunate enough to be attacked directly by a Dhole will get a single roll — to determine if there's enough bits left for a funeral.
- The Lensman books end up using planets as billiard balls against other planets as well as planet-sized masses of antimatter.
- Greg Bear's The Forge of God reaches its climax as a neutronium-antineutronium bomb, deposited in the core of the Earth by malevolent von Neumann machines, detonates, disrupting the entire planet over the course of a few hours with enough force as to put significant portions of it in orbit around the dead, molten remains. A small selection of humanity is rescued before the disaster by another group of friendly von Neumanns who had failed to stop the attack.
- Arthur C. Clarke:
- In Firstborn (in the Time Odyssey saga), has a Class X-lite, with the Q-bomb hitting a planet which will create strange quantum effecst on space-time that will basically rip the upper layer of the planet off. This happened to Mars, when the Martians were eliminated by Firstborn. When Mars gets hit a second time after the Martian from the pocket dimension was contacted by humans and managed to make them divert the Q-bomb, Mars was destroyed completely. The planet's redirection into the sun by the Firstborn (listed in Sunstorm example above in Class 5) is also Class X.
- In Clarke's Odyssey series, "something wonderful" happens to the planet Jupiter. Though it isn't mentioned in the films, Dave Bowman detected life on both Jupiter and Europa; the beings who control the Monoliths deliberately sacrifice Jupiter and its inhabitants to support the Europan life, which they considered to have more potential as intelligent beings.
- In Eric Nylund's Signal to Noise, not-so-nice aliens provide humans with a teleportation system which is powered by the rotational inertia of the planet. The aliens then abuse this system to blow up the Earth, as well as an unrelated detonation of Mars by some post-humans trying to get away from Earth as fast as possible.
- In The Saga of Seven Suns, the Faeros do this to the Moon. Yes, chunks do threaten Earth, but a coordinated response is possible. Additionally, humans destroy a brown dwarf more than 13 times the mass of Jupiter inhabited by Hydrogues, who then obliterate four moons around that once-planet-now-star (Class X destruction), declare war on humanity and the Ildirans, attempt to destroy two human planets, manage to destroy one Ildiran (two would-be Class 3s except other parts of humanity help them, and one Class 4-5 forcing an evacuation of the few who survive up to that point), had attempted to obliterate three ancient races previously, make a second (or possibly even further in) attempt on two of them, destroy a number of skymines, which given the size of the machines and their crew could count as Class 0s, to name a few things that happen.
- In Orson Scott Card's Ender’s Game the title character unknowingly destroys the Bugger home world using the Molecular Disruption/Detachment Device (alt. MD. Device, "Dr. Device", "Little Doctor").
- Michael Reaves' The Shattered World is a fantasy novel about a world that already suffered a Class X, but without losing its civilizations or ecosystems. The planet broke apart, but some fast action by the world's wizards kept its many fragments orbiting one another in an envelope of breathable air. The sequel, The Burning Realm, is about attempts to avert the belated Class 3 and Class 5 consequences of this Apocalypse before these orbit-sustaining spells wear out.
- This is Ruin's immediate goal in Mistborn, and he comes uncomfortably close to succeeding. Because he's a literal god of entropy and decay, it's implied that having accomplished this he'd then keep marching up the scale if left unchecked.
- In When Worlds Collide by Philip Wylie and Edwin Balmer, the Earth is about to be hit and destroyed by the larger of a twin planet. Fortunately the smaller planet is drop-in replacement for Earth. The story (which arguably is the ur-creation that gave rise to stories like Flash Gordon and the many similar tales that followed), revolves around the attempt of a group of scientists to build a pair of rocketships to escape a world facing destruction.
- In Stephen King's one-act play "An Evening at God's," The Almighty is sitting at home in his easy chair, drinking a cold one and trying to watch a sitcom. The Earth hangs in between Him and the TV, blocking His view. Annoyed, He reaches out and crushes it into powder.
- In The Culture series, planetary annihilation is practically a casual event. So much so, that in The Hydrogen Sonata, when a Culture Mind performs a precise hyperspace jump into an underground tunnel, it was quite aware that even the tiniest error in the maneuver would have destroyed the entire planet.
- In The Long Earth, the Gap is an alternate reality in which the Earth is simply gone, presumed to have been destroyed by a massive impact with one or more other celestial bodies.
- "The Midnight Sun", a third season episode of the original Twilight Zone presented a scenario in which Earth's orbit had changed course, drawing the planet closer to the sun with each passing day. It turns out to be All Just a Dream, with a twist (a mandatory trope in the Twilight Zone, really). The main character wakes up relieved to be feeling cool and comfortable, unaware that the Earth really has changed it's orbit, only now it's moving away from the sun.
- Doctor Who has a number.
- The home planet of the classic series Cybermen, Mondas.
- The eponymous "Impossible Planet" (causing the deaths of hundreds of Ood).
- Martha planned to use the Oster Hagen Key to blow the Earth up with strategically-placed nukes so that the Daleks couldn't go through with the death of reality itself.
- The constant jumping between realities in the series 2 finale also risks the two Earths to crash into each other. Doesn't stop Rose Tyler trying to get to the Doctor.
- In "Boom Town", Blon Fel-Fotch Passameer-Day Slitheen plans to use the force of the Rift to tear the Earth apart, riding her tribophysical waveform extrapolator to safety.
- Another example from the classic series, in "The Pirate Planet" there's a 'planet' (more a space craft, but the inhabitants are unaware of this) which eats other planets. When it is finished eating, it makes a hyperspace jump to another planet and starts eating again. It's better than it sounds.
- Babylon 5's Class X member is the Vorlon Planet Killer, which, in accordance with a philosophy of swift and terrible justice, simply obliterates the entire planet being targeted, unlike its Shadow counterpart which leaves the planet intact but lifeless and is therefore only a Class 6. There is some contention over the Vorlon Planet Killer's effectiveness as a Class X weapon, as some of the planets attacked had survivors and atmosphere (as opposed to the planet Arcata 7, which post VPK contact is described as "not there anymore"), though one can get around that by assuming the Shadow bases for said planets were on their moons. The Vorlons would have blown those up, raining down devastation on the planet but not instantly killing absolutely everyone.
- Odyssey 5
- Star Trek gave us the Doomsday Machine, which would break up a planet into smaller chunks and then eat them, and the Xindi Weapon from Star Trek: Enterprise.
- In Star Trek: Voyager, the episode "Scorpion" features Species 8472, which blows a Borg planet to pieces with just 9 small ships.
- The titular ship of Lexx had only one weapon: a Wave Motion Gun that destroyed planets in glorious fashion. In point of fact, any place the Lexx visited was either destroyed by it or something worse (see Mantrid in Class X-4) including the afterlife and in the finale, Earth itself.
- In Andromeda, a planet can be destroyed by either firing a slipstream core at the planet, or by chucking a Nova Bomb at it (though planets hit by Nova Bombs more fall apart than explode).
- While more notable for their Class X-2s, the Stargate Verse has seen its share of destroyed planets. In fact, when Stargate Atlantis had its Gondor Calls for Aid in the fourth season, the Traveler leader is dumbstruck when the Atlantis team casually suggest blowing up the Asuran homeworld.
- In LOST, not entering the numbers into the hatch every 108 minutes and removing the plug from the Island's source is thought to destroy the Earth.
- Season two of the Power Rangers sees Lord Zedd building his own zord Serpentera, a giant craft specifically stated to be capable of wiping out entire planets. In the episode of its introduction, Zedd takes Serpentera, follows the Rangers to a deserted planet, and destroys it. Luckily, with the sheer amount of power it uses, Serpentera runs out of power really quickly, making it a very ineffective weapon in the long-term.
- In the BBC docudrama End Day, the final segment depicts a possible (albeit extremely small chance) result of the Large Hadron Collider (though not called by that name) being turned on. The entire planet gets sucked into a newly formed Black Hole, basically.
- Old Alphatia met this end, forcing the Alphatians' ancestors to emigrate to the Mystara setting. It was an academic dispute between rival factions of archmages that kicked off this particular Earth-Shattering Kaboom.
- Warhammer 40,000's aptly-named Planet Killer and Blackstone Fortresses.
- The Blackstone Fortresses can combine their beams to exponentially increase their effect. One is a Class X, disintegrating the planet by firing the Warp at it (compared to the Planet Killer, which leaves enormous quantities of debris), but three or more could qualify as a X-2, since it is capable of destroying a star, wiping out the entire system with it. Abaddon has two. There were six of them.
- After the Horus Heresy, a freak warp storm obliterated the Dark Angels' homeworld, Caliban, leaving only a scattering of debris. Their fortress-monastery, the Rock, miraculously survived intact. It was refitted with void shields, engines, and atmospheric controls, and now serves as the Angels' mobile base of operations.
- The planet Eris was blown up in Rocket Age.
- Planet annihilation is possible in Star Ruler. Simply park a big enough ship nearby, order it to attack, and the ship will bomb the planet to the point where the planet will break up.
- In Kingdom Hearts, The Heartless will do this to a world if they rampage across it unchecked.
- Super Metroid: Mother Brain's self-destruct sequence destroys Planet Zebes.
- And of course Phaaze in Metroid Prime 3 goes boom, thanks to Samus. Hey, it was aiming for multiple Class 2 catastrophes anyway due to The Corruption, so she beat it to the punch!
- And a Buy One, Get One Free deal in Metroid Fusion: Samus executes a Colony Drop of the Biologic Space Labs station onto Planet SR388, annihilating both bodies.
- Commander Keen episode two (entitled The Earth Explodes!) has the villains of the first episode position a planetary destruction ship in orbit over Earth. If you screw up, you get to activate it. Guess what happens.
- High level Overlords in Disgaea are usually capable of destroying entire worlds in giant Earth-Shattering Kabooms. It's best not to get them mad enough to do this.
- In Master of Orion 2, the player could research, build, and mount a stellar converter on a large enough ship and wipe out entire planets with a nifty movie showing the massive explosion. This typically doesn't eliminate the empire that occupies it, but it does remove the planet from play permanently. Though if the system still has a colony, the resulting asteroid belt can be used to build a new planet. Even better, all planets constructed this way have the same size, which may be larger than the original one. Also, it is possible to avoid the "no terraforming on toxic planets" rule this way, making this a very rare example of using a Class X as a reasonable (if abusive) step in terraforming.
- Also, the newly reconstructed planet can easily be bigger than the original one since all planets built from asteroids are the same size, making this actually a Class 0, unless you happen to lose your last planet in this fashion.
- Master of Orion 3 also has the Stellar Converter, but it was sadly de-powered to Class 6 level, leaving the planet an un-colonizable, lifeless cinder, but otherwise intact.
- Final Fantasy VII. Sephiroth's plan for his planet was to crash Meteor into it, thus forcing the Lifestream to stream out of the impact point in the planet's death throes. Where Sephiroth will absorb the entire Lifestream, become a god, and use the planet's lifeless husk as a giant spaceship to explore other worlds.
- Cyborg Smoke's gloriously OTT (and immediately retconned) fatality from Mortal Kombat 3.
- In the cult DOS game Captain Blood, YOU could nuke a planet into tiny pieces of VGA debris, though sometimes this would make the game Unwinnable.
- Though possibly not a perfect example, World of Warcraft has Outland, which is the result of portals ripping the planet to bits, leaving only a large continent-sized chunk and several hundred minor pieces of debris. Yet the place still supports a few thousand inhabitants despite by logic lacking an atmosphere and dangerously close to a planet that would drag the left over planet chunks into fiery death...
- Of course, Outland isn't floating in space. As the Earth-Shattering Kaboom that transformed Draenor into Outland was a result of dozens of interplanetary portals straining the planet, Outland was tossed into the Twisting Nether, which explains its complete disregard for physics.
- Galaxian 3's bad ending (whether you fail to destroy all of the power relays or die in the middle of your journey) has Cannon Seed using its planet-fueled Wave Motion Gun to blow up the Earth into "fragments smaller than California."
- Take a guess at what the Planet Buster in Spore does? There's a reason if its use is forbidden by the Galactic Federation...
- This happens to Palma in Phantasy Star II, while Motavia suffers a Class 2 shortly after the end of the game.
- The entire story of Shin Megami Tensei III: Nocturne is based around the premise of rebuilding the Earth after it is transformed into the embryonic, demon-infested Vortex World as the result of an event called the Conception. The Earth as you once knew it, and any living thing outside of a small hospital in the middle of Tokyo, is utterly destroyed. This happens in the first ten minutes of the game, by the way.
- In Ratchet & Clank, Chairman Drek tries to do this twice- first with the Planet Buster Maximus to destroy Hoven, and again with the Deplanetizer to destroy Veldin, the latter being used to blow up his new planet (and him).
- The Planet Eaters in Lunar Knights are able to trigger one of these, especially when its governing Immortal decides keeping it around isn't worth it any longer. This can be because the Immortal is bored, because they just hate the people on the world, or because their plot to impose eternity upon the cosmos goes off the rails. Alice is a lagomid survivor or a descendant thereof (Sheridan explicitly says a Planet Eater visited her homeworld), while the titular Lunar Knights cause Polidori to trigger its self-destruct before it can do the same to theirs (and shoot him down before he can attempt a Class 4/5 himself). When he's revived in the optional epilogue, Dumas states that this act of rebellion has not gone unnoticed by the rest of the Immortals, but we haven't seen this play out so far...
- While not directly in the game it is revealed from an Aperture Investment Opportunity video that the Portal Gun is capable of creating a black hole that could destroy the Earth.
- An unusual version happens in Asura's Wrath, where it is a planetary-sized being that gets destroyed this way, Wyzen gets punched to death and explodes after turning into the planet sized Gongen Wyzen.
- This is also narrowly averted in the last episode where Gaia is almost torn apart by a gigantic laser.
- In Might and Magic VI, if you don't get the Ritual of the Void from Archibald Ironfist but go ahead and destroy the Reactor anyway — or if you have the Ritual but teleport out of the Hive rather than leaving by way of the exit — you blow up the world. You were warned, fercryinoutloud.
- There was a reason the aliens were afraid of The Maw. It's too bad their maximum-security specimen (and you) escape when their ship crash-landed. With nothing else in the offing, you and Maw work together to fight for your freedom. However, it becomes clear that Maw has an ever-growing appetite for anything. He climbs up the destruction scale as you progress and, by the end of the game, reaches this level... by eating the entire planet (you escape in a spaceship). Worse, the implication in the closing credits sequence is that Maw is not done yet.
- Your Eater does this in the "Bad" ending of Chimera Beast. It then proceeds into a Class X-2 and maybe even X-3 as it starts destroying more planets in its way. And the cause of all this is... you, the player.
- In Machine Knight, Frain's original mission is to find a way to save his world from the "black sun" that science accidentally created. The opening narration states it's simultaneously eating up the last of the sun's energies and pulling the planet dangerously close, so depending on if the sun eventually goes nova or if there are other planets nearby, it could even be upgraded to a class X-2.
- In Saints Row IV, the Big Bad casually blows up Earth within the first few hours of you starting the game. The rest of the game is the Saints trying to avenge it by killing him and destroying his empire.
- This very concept is the entire idea behind the RTS game Planetary Annihilation, though what would be lower levels of Apocalypse How are certainly possible.
- Turned on its head with the Planet Eater of Casey and Andy. He's designed to eat the planet Earth but, being about the size of a hamster, can only do it one bite at a time.
- This is what will happen to the world of The Order of the Stick if The Snarl gets released - and it IS what happened to the previous world before the existing one was made. (Probably.)
- In Servants of the Imperium, a moon the characters visited began falling apart as collateral damage from a space battle going on in orbit around it. Specifically, it was hit by a single stray Lance shot. But, this is the Warhammer 40,000 universe, so what do you expect.
- The fight between Goku and Superman in Death Battle basically ends with the world's destruction.
- Tech Infantry blows up Earth's moon in this way, which does not do good things for Earth.
- In the Whateley Universe there was a sundering, which effectively destroyed the elves, their home, and their civilization. Their souls survived to arrive on Earth in a few instances, and their servants, the weres, were sent to Earth before the end, so this may be a subversion of it.
- In The Demented Cartoon Movie, the world is continually either blowing up or crashing into the sun.
- In Fine Structure, this happens to the Earth as a side note during the Final Battle. Barely any human casualties though, thanks to the intervention of some really advanced alternate universe humans with copious experience in large-scale split-second rescues. They even build a new planet afterward.
- The Chaos Timeline faces this threat at its end. (Cause: Nano Machines.)
- One article at Things Of Interest discusses why and how to destroy the Earth. Destroying humanity is not good enough, and ideally the destruction would be permanent.
- In Worm, the alien entities that granted people superpowers do this as part of their life cycle, obliterating the planet they parasitize in all possible realities.
- Depending on whose lore you read, Lord Helix and Red were attempting one of these at the end of Twitch Plays Pokémon Crystal. The Godslayers had the task of stopping them from doing so, a task which they succeeded at.
- Titan A.E.: Though a handful of humans evacuate.
- Marvin the Martian tried to accomplish this, but was repeatedly thwarted by a dangerous Earth creature. In Duck Dodgers in the 24˝th Century, Planet X, the planet of the shaving cream atom, is blown to pieces by Duck Dodgers and the Martian one-upping one another.
- What the alien installation did to Mars in Exosquad and what Phaeton plans to do to Earth in revenge.
- In Shadow Raiders, the Beast Planet eats other planets, as demonstrated with planets Water, Tek, Fire, the Prison Planet, and Reptizar. Another planet was blown up by setting a crap load of explosives next to its (nonfunctional) world engines. The Beast ate the remaining chunks. Given that the Beast Planet is not only capable of self-propelled intergalatic flight, but actively seeking out new planets to consume, it could be taken as an example of X-2.
- In an episode of Gargoyles, Fox and her mother are working with some nanomachines which escape and begin a Grey Goo scenario (below), where everything it doesn't turn into more nanomachines is restructured into unchanging order. Since it's meant to grow and evolve it will eventually engulf the entire earth (the heroes only have as much time to stop it as they do because it's reached it's current bounds and will take some time to gain the capacity to come further). They eventually stop it by sending Goliath and Dingo into the Dreaming, where they discover they can communicate with it. Dingo manages to convince it to protect the earth rather than destroying it by suggesting that instead of mathematical order it try law and order, which is similar, but requires less extinction.
- Pinky and the Brain. Episode: 'It's Only a Paper World'. Pinky and the Brain move everyone to a duplicate Earth next door so that Brain can conquer the empty Earth. Then it gets smooshed by meteorite.
- In Futurama, one of Fry's lifelong desires was to blow up a planet. They do it one afternoon.
- After being mined hollow due to containing starship fuel, the planet Vergon VI implodes on itself. Nibbler manages to eat most of the rescued wildlife too.
- Green Lantern John Stewart is accused of causing a chain reaction leading to this in Justice League. It turns out that it was actually a hologram.
- In Dexter's Laboratory, Dexter and Mandark bicker over each other while forgetting about the meteor shower that destroys the Earth. This is ignored the very next episode.
- The planet of Thundera suffered this fate in the beginning of Thundercats, forcing what was left of the Thunderans to get off the planet and find a new world to call home.
- This occurs in Koko's Earth Control, a short cartoon from 1928. Fitz the Dog pulls a lever that causes the end of the world, and after a series of humorous yet terrifying events, the earth explodes with an Earth-Shattering Kaboom. The apocalypse then extends to the real world, with buildings collapsing and shaking, but this apocalypse remains a Class 6 or lower.
- Unicron threatens Earth with this in Transformers Prime, but not via his usual method. In this case, Unicron instead slumbers at the core of planet Earth, which formed around him, and his awakening would shatter the planet into uninhabitable pieces.
- The (in)famous and controversial Grey Goo scenario. Poorly programmed nanomachines go all von Neumann on all matter with which they come in contact, turning it into more poorly programmed nanomachines that do the same thing until every bit of matter within reach has been turned into poorly programmed nanomachines.
- There's also the Strange Matter apocalypse. Same thing, except with unstoppable strange quantum matter - think of the Earth melting like ice cream in the hot sun and evaporating.
- Some scenarios for the origin of the Earth-Moon planetary pairing suggest that a somewhat larger "Earth 1" was hit by Theia, another, Mars-sized planetary body. This impact tore off a huge section of its surface, leaving behind our present "Earth 2". The dislodged debris settled into orbit as a ring, then gradually congealed into the Moon over millions of years.
- Models show that a few billion years from now, Mars is all but confirmed to pass too close for comfort from Earth note , with a small chance of frontal impact.
- Gamma ray bursts.
- Only if it happens really close to the planet, like in the same solar system or a few light years away. A more likely scenario for a gamma ray burst-based apocalypse would be "merely" having the side of the planet facing the blast completely sterilised while the other side burns as the atmosphere catches fire.
- The distance for mass extinction (this one would dwarf anything Earth has seen before) would be about 1,000 parsecs. The distance for "Farewell, atmosphere." would be 500 parsecs. A parsec being about 3.26 light-years. GR Bs emit obscene amounts of energy, ejecting matter from the star at 99.995% the speed of light. Still, there'd still be a planet. Granted, there would never be life on it again...
- Any kind of interstellar space drive can easily be used as a planet killer. A slower-than-light relativistic starship doubles as a relativistic kinetic kill weapon, releasing awesome energies on collision with a planet, leading to at least a Class 5 and possibly a Class X. The speculative Alcubierre, Cleaver-Obousy, and White warp drives are shown to release monstrous showers of radiation on arrival. If any of these will ever be built, no one's giving such power to some space opera trader, smuggler or another private space dog, of course.
- Older theories for the formation of the asteroid belt put forward the idea that it was all that was left after a planet that occupied that orbit broke up. Of course, as science marched on, it's now seen as more likely that the asteroids are simply remains of the solar accretion disc that didn't get a chance to form a planet in the first place.