Artistic License Space.
Hollywood is not interested in teaching or even researching physics, and generally doesn't even depict normal explosions on Earth accurately, so it's no surprise that explosions in space rely on Rule of Cool rather than science. In the movies, explosions in space work pretty much the same way explosions on Earth would (or rather the way film-makers imagine they would, with lots of red flames and smoke).
In reality, space has no air to transfer the explosive energy to. Thus, explosions would have an initial brilliant flash, and the resulting spherical fireball and debris would travel away from the point of explosion far too fast for the eye to see. Do note that without any atmosphere or gravity to act on the debris, it will continue on at full speed until it hits something, meaning such an explosion could actually be more dangerous than it would have been in an atmosphere.
Nuclear explosions would be similar, but with a much brighter flash, and little or no visible debris since it would be vaporized.
Explosions in vacuum on the surface of a planet, moon, asteroid etc. will look similar to those in zero-g, but any debris that does not achieve escape velocity in the local gravity field will arc back down and rain to the surface. In low gravity, this could take minutes or even hours.
Further, if a spacecraft blows up, the explosion should have the same velocity as the craft did (possibly altered by the velocity of whatever hit it). I.e., the boom should keep moving. Many movies and shows have a fast-moving craft turn into a stationary explosion (relative to the camera).
Above all, explosions in vacuum would be silent.
In many cases, this is caused by the method of special effects: actual pyrotechnics in an atmosphere. It should be noted that this is generally considered an Acceptable Break From Reality by the majority of the audience. Some works even try to find ways to work around it. One way is fictional elements used as fuel for ships, which are very flammable.
Many Hollywood Explosions In Space will also include a Planar Shockwave.
This is such an ubiquitous trope that only aversions and subversions should be listed.
- Most explosions in space combat scenes in most Gundam series' follow the more realistic quickly-fading spherical explosion pattern. There usually doesn't seem to be much debris, though, but it may just be vaporized by the Mobile Suit's compact reactors failing catastrophically.
- Macross is also another big user of the spherical explosions, in or out of space.
- Planetes, being a hard science fiction, averts this. When a space center on the Moon where a giant spacecraft engine is constructed blows up, an immense cone of ejected matter is shown, in a realistic and terrifying way.
- In the DCAU tie-in Justice League comic story "Disarmed", Green Lantern evicts an alien bomb off of Earth, making a comment that he never gets used to how quiet explosions are in space. The explosion is represented primarily as a sphere of light (with pointy bits on the compass points).
- Mostly averted in Bait and Switch and Red Fire, Red Planet, a pair of Star Trek Online fics with Character Overlap. Ships that suffer a warp core or fusion bottle breach tend to be described as going up in a "retina-searing white flash" or something similar. Other destroyed vessels tend to leave large chunks of themselves behind, such as a Jem'Hadar attack ship that had its front half blown away by a shot to the torpedo magazine.
- Rocketship Voyager. During the climatic battle against the Psiborg Collective inside a decompressed docking bay, one of the Space Marines is eager to Nuke 'em, but it's pointed out that a) the lack of air reduces the effectiveness of nukes with no blast wave, and b) Voyager is surrounded by an electromagnetic field to keep out cosmic radiation, so if you set off a nuke inside that field it concentrates the radiation there like the Van Allen belt.
- In 2001: A Space Odyssey when Bowman blows the explosive bolt hatch, the sound of the explosion is cut short by the decompression.
- In Silent Running, nuclear explosions in space are just circular flashes that fade away.
- Shown accurately once (except for the sound) in The Fifth Element when Korben blows off the docking bay doors to escape the hotel, otherwise, used in every other explosion in the movie.
- In Apollo 13, the explosion accurately depicted the real life event, except for the spacecraft careening about from said explosion. The venting of a leaking oxygen tank kept pushing them about for a time.
- Done mostly correctly at the tail end of The Avengers (2012). The nuke that Iron Man steers into the enemy mothership detonates as an expanding sphere, with no Planar Shockwave or other Hollywood contrivance. Not quite right, but closer than Hollywood usually gets.
- Most of Star Wars plays this trope quite straight, but in the climactic assault on the first Death Star, one unfortunate Y-Wing is shown continuing to move as it is destroyed.
- Also done correctly with the orbital cascade effect in Gravity.
- Interstellar only has one explosion, which is justified as it is fueled by oxygen form inside the Endurance and realistically is soundless observed from another spacecraft.
- Star Trek movies repeatedly have played this trope very straight.
- In Star Trek II: The Wrath of Khan, it's revealed early on that the sixth planet in a star system exploded, causing a shockwave that knocked the fifth planet off it's orbit, turning it into a desolate wasteland. Mike Okuda points out in the commentary that shockwaves do not propagate through the vacuum of space.
- In Star Trek VI: The Undiscovered Country, Praxis' explosion produces a planar shockwave that knocks everyone on the bridge of the Excelsior out of their chairs, those sleeping out of their beds, etc. As with the above example, shockwaves do not propagate through the vacuum of space. This is handwaved by Commander Valtaine referring to it as a "sub-space shockwave," though it isn't made entirely clear.
- In Star Trek: Generations, the plot revolves around a missile of sorts that can stop all nuclear fusion within a star. The idea is that without the star's gravity to change its course, the energy ribbon would be redirected to the surface of the planet the villain is on. This, of course, would not produce a shockwave (since, at the risk of being repetitive, shockwaves don't propagate through the vacuum of space), and hence not destroy any of the planets immediately, though the people living in the Veridian system would presumably freeze to death without the heat of their sun, eventually. But because dramatic tension must be maintainted, a shockwave is seen destroying Veridian III.
- There are a few times in Our Friend Power 5 when giant, fiery explosions happen in the middle of space, due to the characters being aliens engaged in combat.
- In the Honor Harrington series, ships that have their fusion bottle fail just have a "single, eye-searing flash," and then are gone. It's also mentioned that nuclear warheads are only useful as weapons in space if they get a direct hit (which is highly unlikely, though it does happen on occasion), which is why missile weapons had moved on to using bomb-pumped lasers by the start of the series.
- In Matthew Reilly's Area 7, when a space shuttle gets hit by a missile, it simply cracks.
- In the American Robotech novels, explosions in space are always spherical.
- In The City Who Fought, a starship whose drive systems are going critical explodes near the protagonists' space station, and the resulting debris field makes venturing outside extremely hazardous for quite a while.
- The History of the Galaxy series generally tends to describe explosions in space correctly. Usually, the danger is not the explosion itself, but the debris flying from the exploding ship or station in every direction at high speeds.
- In another novel, a hyper-advanced ship (officially classified as a light cruiser but with enough firepower to take out a conventional fleet) is mentioned to be armed to the teeth with nuclear missiles. The author then proceeds to explain that, in space, this really isn't as dangerous as it sounds. With advanced point-defense systems and EM shielding (protecting from nuclear radiation and EMP), a ship can be effectively immune to a nuclear barrage, as nuclear explosions (without any matter to "feed" on or air to move) only have an effective range of a few miles.
- In The Lost Fleet, ships explode in a brief bright flash only in two cases: reactor containment fails, or two ships collide at an appreciable fraction of the speed of light (ships normally maneuver at 10% of c). In both cases, little is left of the ship after the flash. Most ships that are destroyed in battle simply break apart and continue on their original trajectory, as pieces start to move apart.
- In Robert A. Heinlein's Between Planets it is done correctly when Circum-Terra Station was destroyed by a nuclear weapon. The blast was described as a second sun, blazing white, and as an expanding, perfectly geometrical sphere. The story also explicitly states that there would not be a mushroom cloud in the vacuum of space.
- Track (a 1980's action-adventure series by Jerry Ahern). In "Revenge of the Master" a neo-Nazi bomb maker plans to explode a bomb on board the Space Shuttle, and gives some thought to how the vacuum will affect the explosion.
- In the 1940's Venus Equilateral tales by George O. Smith, the eponymous Space Station is being threatened by a Space Pirate. Various means of defense are considered including guided torpedoes. However it's pointed out that explosives have little effect in a vacuum as there is no atmosphere to create a pressure wave, shrapnel might not penetrate the hull and even an armor piercing warhead has to hit the fast-moving spaceship in the first place.
- Like every Sci-Fi show, Stargate SG-1 and Stargate Atlantis have this. However, when they use nukes, the explosions are at least spherical and without a mushroom cloud.
- In Firefly, damaged ships (such as a derelict freighter blown up by an Alliance cruiser in "Bushwhacked") simply break up, with the broken parts drifting in the trajectory of the ship. There was also no sound of the explosion of break up (which was true for most space shots in Firefly)
- There are lots of these in Star Trek after a Standard Starship Scuffle with an enemy vessel.
- In Battlestar Galactica, explosions usually die out quickly and fiery explosions (which are caused by oxygen in the ships that blow up themselves - the reason why Cylon raiders hardly ever blow up but just disintegrate mostly) appear 'smeared' by velocity. Also, nuclear explosions do appear mostly as 'just flashes' as described above, without the trope-ish fireball and/or mushroom clouds. While capital-ship shots were generally silent, smaller fighter craft generally had full sound in space. The creators fully intended for all space battles to be silent, but upon viewing the results, decided it was too unnatural and inserted sound effects. In a nod to original intent, all sound effects in space are still noticeably subdued.
- Averted in The Expanse. When a ship is nuked, it breaks apart and vanishes in a bright flash and spherical blue explosion. Another nice touch is that ships don't actually explode without the application of explosives, as seen in "Doors and Corners," when Rocinante wins a space battle by Swiss-cheesing their opponent with PDCnote rounds, killing the crew without actually blowing up the ship.
- Though the visual isn't discussed, explosions in GURPS lose about half of their power when in space due to lack of atmosphere.
- In EVE Online, the explosion effects look pretty much correct according to what is described above. They are slowed down, however, so that the players can savor in the shiny afterglow of the ship they just helped blow up.
- Nobody's perfect, though: Torpedoes still give a great planar shockwave. So do large structures when they go BOOM. Every time a Drone Silo is blown up, a planar shockwave comes with the explosion, free of charge.
- They do get the "Explosion moves on original trajectory at original velocity" bit, at least. Sadly, the same can't be said for the wreck that's left behind, though that's so you don't have to go chasing it down when you want to loot it.
- The Sound Effects are justified in game by the simple fact that everything you see as a pod pilot is a VR simulation of actual events, piped directly into your head while you are safely curled up inside your pod full of goo. Apparently early versions of the Pod tech didn't bother with Sound but the lack of it tended to send the (already mentally unbalanced) capsuleers completely insane.
- Star Fox games do this as well, with ships mostly breaking apart after being hit or the classic "BOMB" item going in a perfect sphere.
- Slyly justified in the early PC game Elite. The manual explained that when a ship or similar explodes in space, as well as the flash it produces a burst of radio waves which, hitting your communicator, make a sound just like an explosion.
- While Dead Space games gets the workings of gravity and vacuum right most of the time, in the second game there is a curious exception. In a zero-gravity area (with oxygen) there is a large, roaring fire. Despite the lack of gravity, the flames are reaching "upwards", instead of expanding in all directions.
- In Sword of the Stars nukes produce a small spherical blast in space, and the only other explosives are acid and nanite bombs that leave a sphere-shaped corrosive cloud. And when used in Orbital Bombardment nukes produce a sphere again but substantially bigger.
- When ships are destroyed, their parts continue to travel in the same direction for a few seconds before they blow up. This is even true of Liir ships which, technically, don't move in the Newtonian sense but teleport millions of times per second. Thus, when Liir ships are destroyed, their wrecks should stay relatively at rest.
- The enemy ships in Rodina will turn into a fiery wreck if you shoot them enough. Your ship will also do that if it loses all of its health, or if it catches on fire.
- A Miracle of Science is careful to make sure to accurately portray the behaviour of explosions in space and waste gases from factory smokestacks on the Moon (It Makes Sense in Context, amazingly) that can be seen in the background of one page. The comic's creators really have Shown Their Work.
- Starslip lampshades this trope in a storyline about the Astry's combat exercises. One of the captains complains that the battle doesn't feel like the real thing — because the damage is all simulated, and there are no explosions in space when a ship is hit.
Capt. Zarde: Pyew! Pyow Bwommmkssrrch! Augh! This sucks!
- The Inexplicable Adventures of Bob! has shown space explosions twice so far. The first one was accompanied by the Un Sound Effect "SILENT KABOOM!" The second one quickly morphed into a fireworks display, with the onlookers' screams changing to "Oooh! Ahhh!"
- In SuperMarioLogan's "Bowser Junior Goes To The Sun!", Junior's Space Shuttle (named Octopus) explodes when it gets too close to the Sun.
- In Il était une fois...... Space, ships in space usually blow up in spherical explosions especially when the Cassiopeian fleet, and especially their Nautilus-class warships, is being obliterated in mass by the Humanoids, that often do not even expand. They always come with sound, however, and in one episode a warship from the Omega Confederation after being hit explodes producing a planar shockwave.
- Back in the day the two Superpowers conducted several series of high altitude nuclear explosions that resulted in fireballs being as cool if not cooler than anything Hollywood could produce well into the age of CGI. Just another example of something that's just as easy to get wrong as right. It should be noted that these explosions were still in the atmosphere, just very high up.
- Nuclear explosions in space would cause damage in a very different way than nuclear explosions in an atmosphere. A nuclear explosion in a vacuum produces a bright flash, a burst of neutrons, and a burst of intense radiation that rapidly declines in effect due to the Inverse Square Law. The actual damage to a target would come from the radiation and neutrons, which would fry the crew plus any electronics, and leave the target highly radioactive.
- The Casaba-Howitzer experiments were attempts to make spaceborne nukes viable, developed to meet the Orion Drive prerequisite of a "shaped nuclear charge". By attaching a thin tungsten plate to a warhead, one gets a beam of atomic fire; by attaching a thick styrofoam pillar to it instead gets a wide "pancake" of nuclear debris. Or so it was thought because the experiments were canned after a treaty barring atomic weapons in space was ratified.
- A faulty spy satellite is said to have been shot down with a missile by the US Navy, to prevent it from becoming a hazard. Note that most satellites are actually still within the atmosphere. (GPS satellites and the geosynchronous communication satellites used by everyday fixed dish antennas are two notable exceptions.)