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[[quoteright:350:[[Film/StarTrekVITheUndiscoveredCountry http://static.tvtropes.org/pmwiki/pub/images/praxis_effect_2737.jpg]]]]

Huge explosions in space turn into fireballs surrounded by unexplained rings of fire/plasma that expand usually on the relative horizontal or vertical plane, often racing just past the camera. Used to make big [[StuffBlowingUp kabooms]] (especially those that [[EarthShatteringKaboom blow up whole planets]]) appear more powerful, and when spheroid shockwaves just won't do.

Perhaps this is done because the expected near-spherical explosion don't feel as big, or because a two-dimensional shockwave resembles that of powerful explosions on earth. In theory, it ''could'' be {{Hand Wave}}d by being an effect of the method of ArtificialGravity, or some kind of rotating generator exploding, or plasma trapped by some great magnetic field... but it usually just gets a pass due to being an [[RuleOfCool awesome]] visual.

Very commonly used in space-based video games, as it is a relatively "cheap" and easily produced effect.

Count on the hero's CoolShip to be directly in its path by [[ContrivedCoincidence apparent coincidence]], allowing him to OutrunTheFireball.

Note: a spherical shockwave that is relatively transparent would look like a planar shockwave viewed from a perpendicular angle; done that way it is not this trope.

Possibly a subtrope of {{Two-D Space}}. See also ExplosionsInSpace for other ways media gets explosions in vacuum wrong.

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!!Examples

[[foldercontrol]]

[[folder: Anime and Manga ]]

* In ''Anime/MagicalGirlLyricalNanoha'', if something is struck by the Arc-en-ciel, a spaceship weapon that distorts time and space to vaporize a target, it will produce these after it gets destroyed.
* The very first episode of ''Anime/TengenToppaGurrenLagann'' has one.
* The destruction of [[spoiler:the black hole]] at the end of ''Diebuster'' spawns a small, rainbow-colored one that promptly twists into an infinity sign before fading away.

[[/folder]]

[[folder: Film ]]

* Possibly the earliest example of a planar shockwave is the self destruction of the Nostromo in ''Film/{{Alien}}'' (1979). From Ripley's POV, it first forms a horizontal multicolored line and then an orange sphere appears behind/inside it. A few seconds later a horizontal shockwave of material hits her ship.
* ''Film/StarTrekVITheUndiscoveredCountry'', when the Klingon moon of Praxis explodes in a double shockwave ring. The effect is occasionally called a [[http://en.wikipedia.org/wiki/Praxis_effect Praxis Effect]] after this prominent example. The shockwave actually gains plot significance here when it hits the starship Excelsior, since it makes the Federation aware of what happened. Most other examples feature the rings mostly for eye candy.
* The Special Editions of the original ''Franchise/StarWars'' trilogy does this three times: once for each Death Star (vertical and horizontal rings, respectively) and once when Alderaan is destroyed. They weren't in the original versions.
** Partially justified with the Death Stars. The trench dividing the two hemispheres is weaker than the rest of the shell, which would cause a (if somewhat smaller) Planar Shockwave. However, the first Death Star exploded vertically, and the second Death Star wasn't completely built yet.
*** ''Film/AttackOfTheClones'' takes it one step further, with the shock bombs dropped from Jango Fett's ship: The resulting explosion is focused into a thin disk shape that seems to simply cut through the surrounding asteroids. Which given that space is three-dimensional makes them extremely ineffective weapons that only work because Obi-Wan seems not to be aware of that fact.
*** A planar shockwave has advantages: the 'blast' effect of a spherical explosion goes down with the square or the radius (4 Pi r[[superscript:2]]). If focused into a planar one, 'blast' goes down with the radius (2Pi r). So if you can aim the shockwave, the mine has a much larger effective range.
**** [[AllThereInTheManual According to Wookieepedia]], the shields on anything smaller than a capital ship would be unable to defend against these charges, supporting this idea that the planar shockwave is in order to produce a much more powerful blast.
** The [[Franchise/StarWarsExpandedUniverse Expanded Universe]] novel ''Literature/DeathStar'' explains the ring produced by Alderaan as the realspace shadow of a hyperspace ripple, produced as a side effect of the Death Star's superlaser being fully charged when fired. Presumably this is also the case when the Death Star itself explodes.
*** This can also be used to explain the ring produced by the Death Star II in ''Film/ReturnOfTheJedi''. According to EU materials, the second Death Star could recharge much faster than the original, so it was likely charged to full power when it blew up.
* ''Film/{{Stargate}}'' features one when Ra's ship blows up.
** This might be acceptable given the shape of the ship. ''Might''.
*** Actually, a better explanation would be the fact that it was sitting on a platform, surrounded by a ring of the as-yet-unnamed material the Stargates were made of, something that was explicitly stated would enhance the blast.
* ''Film/IndependenceDay'' features something similar as the Alien Mothership explodes: The explosion spreads horizontally on the screen, eventually engulfing the camera. Might have looked like a Praxis Shockwave from another angle.
* Used {{egregious}}ly in the ''Film/WingCommander'' theatrical release, in which a character fails to [[OutrunTheFireball outrun a shockwave]] which is half the height of her fighter craft. Despite being the squadron commander, the idea of glancing behind her and pulling up never occurs to her.
** Also, during the ship-to-ship battle between the ''Tiger's Claw'' and the Kilrathi ships, an enemy capital ship is hit with two torpedoes and explodes, emitting a planar shockwave that proceeds to destroy another Kilrathi ship. Apparently, traveling close together, leaving no room to maneuver, is standard operating procedure for the kitties. No wonder a single human ship was able to deal so much damage to the more advanced Kilrathi.
* ''Film/{{Armageddon}}'' has one when the nuclear ordnance exploded inside the asteroid.
** At least this one ''kind of'' made sense, since the asteroid wasn't blown up, but blown apart. The shockwave would have escaped from between the two halves. It still wouldn't have been perfectly planar, but still...
* An apparent example occurs when [[spoiler:Jupiter]] explodes in ''Film/TwoThousandTenTheYearWeMakeContact'', but it is made clear that it is actually the visible edge of a spherical shockwave when it [[OutrunTheFireball catches up to the heroes' ship]].
* The orbital laser station (the ZEUS) in ''Anime/FinalFantasyTheSpiritsWithin'' explodes like this at the end of the movie.
* A rare earth-based example occurs in ''Film/TheTransporter'' when the main character's house is blown up by the bad guys. Seriously.
* Seen when Krypton blows in ''Film/ManOfSteel''.

[[/folder]]

[[folder: Literature ]]

* In the ''Literature/CitiesInFlight'' science fiction novels by Creator/JamesBlish, there is an explosive TDX that only explodes perpendicular to the local gravity field.
* In Neal Asher's books set in the [[Literature/ThePolity Human Polity]], there exist ''planar explosives'' which are allegedly the product of molecular engineering, which produce 2D blasts.

[[/folder]]

[[folder: Live Action TV ]]

* Though averted in ''Series/StargateSG1'' in favor of the usual (equally unlikely) space fireballs, ''Series/StargateAtlantis'' used a planar shockwave when the Asuran homeworld explodes.
** Not to mention EVERY exploding wraith ship. Bonus points for [[OldSchoolDogfight making nearby ships explode too]].
* In a ''SpaceCases'' episode, the two-dimensional shockwave of two exploding Spung battlecruisers (due to double DeadlyDodging) destroys the third one.
* Narn energy mines in one of ''Series/BabylonFive's'' space battles.
* A spectacular one is seen at about 40 seconds into [[http://www.youtube.com/watch?v=koX5UJy4QiI the opening]] for ''Series/PowerRangersLostGalaxy''.

[[/folder]]

[[folder: Video Games ]]

* Heavy bombs and capital ship explosions in ''VideoGame/{{FreeSpace}}'' and its sequel. The "randomly oriented" part is only when 3D shockwaves are enabled in the updated [=FreeSpace=] 2 Open engine. In the original games they were always oriented so you saw the "ring" head-on. In the first game in the series, the shockwaves even looked spherical. The explosion effect, however, is spherical.
* In ''VideoGame/{{Homeworld}}: Cataclysm'', the good guys' {{BFG}} creates one of those upon impact. Also used for explosions of the largest class of spaceships. Explosions have spherical effects, however, regardless of the visual.
* Tactical battles in ''VideoGame/MasterOfOrion 3'' use these for capital ships.
* ''VideoGame/StarTrekArmada'', ''VideoGame/StarTrekStarfleetCommand'' and their respective sequels make frequent use of them. In ''Starfleet Command'', the same planar shockwave effect is used for every ship above the fighter class.
* ''Star Wars: RogueSquadron'' and its sequels feature these whenever a starfighter explodes in mid-air.
* Shows up in the explosion of Zebes in the ending to ''Super {{Metroid}}''.
** We also see Zebes exploding in the same way, but with cooler visuals, in the Adventure mode of ''VideoGame/SuperSmashBros. Melee''.
* In ''VideoGame/SwordOfTheStars'', tactical battles use these. They are actually ''weaponized'' by Chakkars/Chakrams, where the planar shockwave is used to [[ArmorPiercingAttack slice through armor.]]
* In ''VideoGame/TachyonTheFringe'', all spaceships go down with shockwave rings, more noticeable on large ships.
* While most explosions in the ''VideoGame/EscapeVelocity'' series will just be the usual yellow-orange-red atmospheric looking fireballs, the very most awesome ships and weapons exploding will make planer and ring shockwaves in pretty colors.
** Also seen on the splash screen of EV:Nova.
* Averted in ''VideoGame/StarFox64'', where all explosions are [[SphereOfDestruction spheroidal]] (although they end up looking like geodesic balloons due to polygon limitations).
** ''VideoGame/SanFranciscoRush'' series too, where EveryCarIsAPinto and MadeOfExplodium, exploding violently with spherical fireballs in crashes.
** ''VideoGame/StarFoxAdventures'' plays this straight however as most spaceships in the game blow up like this. This is especially apparent when [[spoiler: [[HijackedByGanon Andross's head]]]] explodes at the end of the game exactly like the Death Star did, complete with ship's outrunning the fireball.
* The Scrin mothership in ''VideoGame/CommandAndConquerTiberiumWars'' does this, with an ''Film/IndependenceDay'' beam that creates an expanding shockwave, and anything that gets caught in it also explodes, creating their own miniature shockwaves. This can rapidly spread out of control, destroying an entire base in one blow. That is, if the mothership ''lives''...
** Probably justified in this case. The game takes place on Earth's surface, where gravity allows planar shockwaves to actually happen.
* In ''VideoGame/SeriousSam'', rockets, grenades, cannonballs and ''laser beams'' send {{Planar Shockwave}}s of various sizes along the surface they explode on.
* ''VideoGame/WingCommander Prophecy'' uses an upgraded graphics engine compared to previous games, and is the first game in the series to use 3D acceleration. Among the new visuals is a planar shockwave effect that randomly occurs when a fighter craft explodes. The orientation of the effect appears to be random.
* The Stinkowing in ''VideoGame/Stinkoman20X6'' causes a few when it explodes.
* A number of the graphics used for larger explosions in the ''[[VideoGame/{{X}} X-Universe]]'' games do this.
* In the Xbox version of ''VideoGame/CrimsonSkies'' (''High Road to Revenge''), this happens when you blow up zeppelins (despite being filled with helium).
* ''Veigues: Tactical Gladiator'' plays this straight with the enemy battleship's explosion in the ending cutscene.
* ''VideoGame/WonderBoyInMonsterWorld'' has one at the end after the hero teleports off the planet.
* In ''VideoGame/StarTrekOnline'', visual planar shockwaves result from a number of different types of explosions, though in most cases the actual force of the explosion radiates in all directions. Probably the most commonly seen is the death animation of Romulan warbirds. They get sucked into their own drive singularity, which then explodes in a green planar shockwave as it decays.
* ''VideoGame/StarSoldier R'' includes a planer shockwave in the ending cutscene.

[[/folder]]

[[folder: Web Comics ]]

* In ''Webcomic/RealLifeComics'', when [[http://www.reallifecomics.com/archive/081024.html Tony's space station explodes]]. Given a LampshadeHanging in the following strip:
--->"Tony's gonna be ''pissed''. He hated it when Lucas added those equatorial rings to the Death Star explosions."
* In ''Webcomic/DarthsAndDroids'', which loosely follows the plot of the ''StarWars'' movies, the shockwave bombs from AttackOfTheClones make their [[http://darthsanddroids.net/episodes/0294.html appearance]]. One player explains that they might work like that because of the inverse square law - by concentrating the force into a ring, more damage is done by the ring. In effect, Jango is sacrificing accuracy for power.
* Appears in an extreme long-distance panel in ''Webcomic/SchlockMercenary'', when the F'Sherl-Ganni (Gatekeepers) decide to deliberately detonate the ''t'okjith'' (trans: "very clever, but extremely dangerous thing"; a toroidal singularity trapped in the heart of a star) that was powering one of their ''buuthandi'' (trans: "very expensive thing"; sort of a DysonSphere made up of habitats slung on giant solar sails -- which is actually closer to Dyson's original concept than a solid shell) while under attack from Fleet Admiral Breya Andreyasn's forces, with their cheap wormgate-copy systems producing a ridiculous amount of missiles to force said fleet into the shockwave, with the intention of over-awing the "lesser species" by totally annihilating a multi-national fleet. [[spoiler: [[http://www.schlockmercenary.com/d/20020820.html The fleet escapes]].]] Justified by putting gravity-control devices out in the system's Kuiper Belt to ensure that when it ''does'' blow, rather than the star acting as a giant frag grenade, it rips the fabric of space/time a new one in one particular plane.

[[/folder]]

[[folder: Web Original ]]

* [[WebAnimation/HomestarRunner Strong Bad]] enjoys (causing) these, enough that he considers "coolest explosion I ever saw that had one of those blast-wavy Saturn rings around it that've become so popular lately." as an entire category of the best explosions he's ever seen/caused.
* The intro of the ''Second Reality'' demo does this in {{homage}} to the aforementioned Praxis explosion.

[[/folder]]

[[folder: Western Animation ]]

* The shockwave ring from the first Death Star's destruction is carried over into the parody of the scene in ''WesternAnimation/ThePowerpuffGirls''.
* The Transwarp Wavefront in ''WesternAnimation/BeastWars'' created from the exploding [[ThatsNoMoon Vok Weapon]] was plot-significant throughout the second season. It not only spread outward all the way to Cybertron, but traveled into the future as well.
* In ''WesternAnimation/CodeLyoko'', the main weapon of Megatanks is a vertical planar shockwave.
* In ''WesternAnimation/MyLittlePonyFriendshipIsMagic'', Rainbow Dash causes a ''rainbow-striped'' planar shockwave upon performing the Sonic Rainboom.

[[/folder]]

[[folder: Real Life ]]

* Because stars involved rotate at high speeds, collapsars (a form of hypernova) tend to form hourglass-and-ring shapes.
* Other supernovae look like this because the brightest ejecta forms a thin shell. You can barely see the part that's coming straight at us, but the edges (where our view is tangent to it) look very bright. [[http://en.wikipedia.org/wiki/SN_1987A SN 1987A]] is a good example of this.
* As mentioned above, large nuclear explosions can look [[http://scrapetv.com/News/News%20Pages/Science/Images/massive-nuclear-explosion.jpg something like this]]. However, it's just cloudlike condensation as the invisible spherical-ish shockwave passes through layers of the atmosphere where pressure and water content are right. Depending on conditions, this can produce [[http://3.bp.blogspot.com/_8adFNycaanI/RiXsoHQ3d8I/AAAAAAAAAFs/FJv_0fHjPG4/s400/Bravo%2Bfireball.bmp multiple stacked rings]].
* In the 1950's, the Orion Project studied different ways of directing nuclear explosions. Certain configurations do produce planar outflows of plasma (consider a column of high-density gas in a vacuum. It can only expand towards the sides).
* There are also fireworks that have this sort of effect.
* Whenever a black hole eats a large enough star. The dying star, as it sinks below Roche's Limit and gets torn by the tidal forces, gets spread into a ring structure around the black hole, called an accretion disk. The often relativistic rotation of the hot electrically charged plasma in it creates huge magnetic fields and electric currents in the direction perpendicular to the disk's plane, ejecting all the matter in the black hole's polar region in two enormous relativistic jets, sometimes attended by the powerful bursts of gamma radiation. These "explosions" often continue for days until the whole star isn't consumed.

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