Planar Shockwave



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 kabooms 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 Waved by being an effect of the method of Artificial Gravity, 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 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 Cool Ship to be directly in its path by apparent coincidence, allowing him to Outrun the Fireball.

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 2-D Space. See also Explosions in Space for other ways media gets explosions in vacuum wrong.

Anime and Manga

 * In Magical Girl Lyrical Nanoha, 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 Tengen Toppa Gurren Lagann has one.

Film

 * Possibly the earliest example of a planar shockwave is the self destruction of the Nostromo in 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.
 * Star Trek VI: The Undiscovered Country, when the Klingon moon of Praxis explodes in a double shockwave ring. The effect is occasionally called a Praxis Shockwave 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.
 * StarDestroyer.Net proposed a theory that the planar thing is shipboard visualisation cut-out, noting that:
 * the shockwave was not in realspace (it propagated FTL and the nearby planet was mostly unaffected);
 * the ship had subspace presence and greatly reduced realspace inertia at the moment for cheap sublight acceleration, which happens all the time in ST 'verse;
 * it's improbable for a ship to be accidentally so close to the thin plane of propagation at the range of at least light years.
 * Another possibility is to start with Milky Way Galaxy being more or less a flat spiral. It only makes sense for ships to be very close to the main plane, and since this happened in "subspace" (ahem), it may make sense for the wave to expand mostly along this plane - which would also reduce energy requirements for being so strong at a great range. Either due to anisotropic properties of subspace as such, or the wave was shaped from the start because the equipment that exploded had to be oriented along this plane in the first place due to properties of subspace it was using.
 * The Special Editions of the original Star Wars 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.
 * Star Wars: Attack of the Clones 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^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.
 * It depends on what the warheads were initially made for... But didn't the mines first appear in ground combat? In which case it's a good idea to deposit more energy into targets on the ground or close to it, and less into blasting a crater that's at best wasteful and at worst gives the enemy more cover.
 * The Expanded Universe novel Death Star 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 Return of the Jedi. 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.
 * 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.
 * Independence Day 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 egregiously in the Wing Commander theatrical release, in which a character fails to 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.
 * 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...
 * The shockwave seems to be forming an hourglass shape if viewed from the front, so it does expand at least partially accurately. But this is Armageddon, which has as much basis in real physics as the Stay Puff Marshmallow Man.
 * An apparent example occurs when explodes in 2010: The Year We Make Contact, but it is made clear that it is actually the visible edge of a spherical shockwave when it catches up to the heroes' ship.
 * The orbital laser station (the ZEUS) in Final Fantasy The Spirits Within explodes like this at the end of the movie.

Literature

 * In the Cities in Flight science fiction novels by James Blish, there is an explosive TDX that only explodes perpendicular to the local gravity field.
 * In Neal Asher's books set in the Human Polity, there exist planar explosives which are allegedly the product of molecular engineering, which produce 2D blasts.

Live Action TV

 * Though averted in Stargate SG-1 in favor of the usual (equally unlikely) space fireballs, Stargate Atlantis used a planar shockwave when the Asuran homeworld explodes.
 * Not to mention EVERY exploding wraith ship. Bonus points for making nearby ships explode too.
 * In a Space Cases episode, the two-dimensional shockwave of two exploding Spung battlecruisers (due to double Deadly Dodging) destroys the third one.
 * Narn energy mines in one of Babylon 5's space battles.
 * A spectacular one is seen at about 40 seconds into the opening for Power Rangers Lost Galaxy.

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. SN 1987A is a good example of this.
 * A recent supernovae picture also serves as a good example of a planar explosion. This one is particularly death-starish. Supernova 1987A
 * As mentioned above, large nuclear explosions can look 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 multiple stacked rings.
 * In the 1950s, 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.

Video Games

 * Heavy bombs and capital ship explosions in Free Space 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 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 Master of Orion 3 use these for capital ships.
 * Star Trek: Armada, Starfleet Command 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: Rogue Squadron 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 it exploding in the same way, but with cooler visuals, in the Adventure mode of Super Smash Bros.. Melee.
 * Tactical battles use these in Sword of the Stars.
 * They are actually weaponized by Chakkars/Chakrams, where the planar shockwave is used to slice through armor.
 * In Tachyon: the Fringe, all spaceships go down with shockwave rings, more noticeable on large ships.
 * While most explosions in the Escape Velocity 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 Star FOX 64, where all explosions are spheroidal (although they end up looking like geodesic balloons due to polygon limitations).
 * San Francisco Rush series too, where Every Car Is a Pinto and Made of Explodium, exploding violently with spherical fireballs in crashes.
 * Star Fox Adventures plays this straight however as most spaceship's in the game blow up like this. This is especially apparent when  explodes at the end of the game exactly like the Death Star did in Star Wars, complete with ship's outrunning the fireball.
 * The Scrin mothership in Command & Conquer 3: Tiberium Wars does this, with an Independence Day 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...
 * In Serious Sam, rockets, grenades, cannonballs and laser beams send Planar Shockwaves of various sizes along the surface they explode on.
 * Wing Commander Wing Commander 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 Stinkoman 20 X 6 causes a few when it explodes.

Web Comics
""Tony's gonna be pissed. He hated it when Lucas added those equatorial rings to the Death Star explosions.""
 * In Real Life Comics, when Tony's space station explodes. Given a Lampshade Hanging in the following strip:


 * In Darths and Droids, which loosely follows the plot of the Star Wars movies, the shockwave bombs from Attack of the Clones make their 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 Schlock Mercenary, when the F'Sherl-Ganni (Gatekeepers) had of their buuthandi (trans: "very expensive thing"; sort of a Dyson Sphere made up of habitats slung on giant solar sails ) was under attack from Fleet Admiral Breya Andreyasn's forces, they 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 providing power to their wormgate-copy systems - after 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. 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.

Web Original

 * 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.

Western Animation

 * The shockwave ring from the first Death Star's destruction is carried over into the parody of the scene in Powerpuff Girls.
 * The Transwarp Wavefront in Beast Wars created from the exploding 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.