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In Star Wars, ships burn when hit by laser fire, as in this scene:

An examination of the scene at 2:16 shows the clone pilot along with the flaming pieces of his ship. Why is the ship on fire anyway in space. Isn't space a vacuum?

At 2:27, the ARC-170, after being stricken by laser fire, burns for several seconds. Why does it burn?

In this clip, Anakin's Star Destroyer burns in space before slamming into the Separatist ship.

In all three of these cases (and there are many more), why do the ships burn in space? Is there some sort of explanation?

Count Dooku
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    Because your average viewer - having seen ships burn in space in basically everything else - expects a ship to burn in space. – Anthony Grist Jan 28 '17 at 22:44
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    They aren't lasers, they're beams of plasma. – Null Jan 28 '17 at 22:50
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    Crazy: rocket engines burn in space too. – geometrian Jan 29 '17 at 05:23
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    @imallett They have oxidizers in the fuel. – Count Dooku Jan 29 '17 at 11:35
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    @CountDooku Exactly. Don't you think a spaceship would carry plenty of oxidizer with it? Propulsion, weaponry, life support... :) And oxidizer isn't an absolute - it's a relative thing, and very dependent on ambient conditions (think thermite). Mind you, most flames would be invisible in a vacuum, but they'd be there. – Luaan Jan 30 '17 at 09:40
  • @ApproachingDarknessFish Watch the fight with Count Dooku when they rescue Palpatine. Afterwards, there is a hull breach and the vacuum of space receives some exhibition. – mbomb007 Jan 30 '17 at 16:02
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    You may be interested in some of Cody's Lab videos where he tries to ignite (or explode) various things in a vacuum. Here's a sample: https://www.youtube.com/watch?v=8Cx9mNnky2U – rrauenza Jan 30 '17 at 19:31
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    @Bob “Why can spaceship explosions be heard in sci-fi” is such a tired argument at this point.  It's true this doesn't make sense with present-day (NASA) space technology— however, most sci-fi spaceships aren't powered by rocket fuel.  The best explanation that covers most space-sci-fictions is that “When a futuristic high-energy reactor or energy conduit explodes it gives off a significant EMP, which will almost certainly resonate the hulls of any nearby ships, and thus sound can be heard from inside of any other vessel.” – Slipp D. Thompson Jan 31 '17 at 12:06
  • Comments are not for extended discussion; this conversation has been moved to chat. – Null Jan 31 '17 at 15:15
  • In a Galaxy far, far away, space is not a vacuum. – Callum Bradbury Mar 14 '18 at 14:01

6 Answers6

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All of these ships have a breathable atmosphere inside of them, as well as flammable materials. If oxygen is leaking because of a hull breach, it can burn.

It's also a common misconception that there is no fire in space. We already have flamethrowers that work in a vacuum, because their fuel includes an oxidizer. There are also plenty of materials and things that may burn without external oxygen supply for that exact reason. It's possible, and likely, that the ships are leaking such liquids or gases, which catches fire when in contact with a heated hole in the hull.

Also, the short bursts of "fire" might be leftovers from turbolaser shots - which aren't really lasers, but superheated Tibanna Gas, basically plasma - and not oxygen-fueled fire at all.

That said, rule of cool and lack of scientific knowledge is the most likely cause of those fires, and not actual physics.

user151841 also raises a very valid point - the flames serve to tell the viewer just how extensively damaged those ships are. We, as Earth-stuck people, are used to the idea that damaged vehicles (or other constructs) catch fire when heavily damaged.

Edlothiad
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Petersaber
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  • I agree with your point, but if the hull of Anakin's Star Destroyer was breached, then why is he not dead due to the oxygen rushing out of the ship, because the ship was burning for some time, and most of the oxygen in the ship is being spent to fuel these fires. I assume that probably a section of the ship as repressurized. – Count Dooku Jan 29 '17 at 12:02
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    @CountDooku those ships are gigantic and have active life support systems. There is a LOT of oxygen to burn, and depending on the size of the breach, it might take a while to leak. And most likely those fires are an effect of those leaking chemicals (Tibanna gas from weapon systems?) rather than air alone. And you raise a very good point, sections of the ship were most likely blocked out. – Petersaber Jan 29 '17 at 12:38
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    Maybe not the "rule of cool" but an indication to the audience of what's going on. If you see a giant space ship with some holes in it, what's going on? Is it minor damage? Major? Is it destroyed? If a ship stars blowing up on fire, the audience immediately knows that "this ship is out of commission". – user151841 Jan 30 '17 at 03:42
  • @CountDooku The basic idea is even simpler. On Earth, most fuels use the readily available oxygen in the air - those fuels wouldn't burn in a vacuum (the main exception being high explosives). However, in a spaceship, that would be ridiculous - you're going to bring both fuel and oxidizer (just like HE). And when those mix, you get fire. Also, depending on conditions, previously inert things can become fuel and/or oxidizer - thermite is a real-life example. There's plenty of oxidizers everywhere in a space battle with plasma bottles (turbolaser shot) flying around :) – Luaan Jan 30 '17 at 09:36
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    Even something like thermite is difficult to get to sustain combustion in a vacuum and even then, it doesn't emit much at all in the way of flames or light. Gases like oxygen disperse incredibly rapidly in vacuum because molecules at room temperature have a very high velocity. Combustion of the sort shown in Star Wars requires pressure as well as a supply of oxidiser. Space lacks the required pressure. – RedGrittyBrick Jan 30 '17 at 16:05
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    @Luaan hey, maybe shields are still operational and the atmosphere is leaking into the shielded area, not dispersing (because shields), and this is why it burns continually – Petersaber Jan 31 '17 at 09:17
  • @Luaan "when those mix, you get fire" Only in the case of hypergolic combinations. There are many rocket fuels in real-world usage that are highly energetic, but require something to start the chemical reaction. Of course, they aren't energetic enough to power an interstellar spacecraft, but of course neither is your average flamethrower. – user Jan 31 '17 at 15:11
  • Comments are not for extended discussion; this conversation has been moved to chat. – Null Jan 31 '17 at 17:04
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Also, in the Revenge of the Sith battle: Canonically it takes place in the upper atmosphere of Coruscant, not space, so there is some atmosphere. They also use this to explain why the ships fall when they're hit and why wings were so important to Obi-wan's starfighter.

Sera
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    Ships would fall even if there was no atmosphere - planet's gravity well far outreaches it's atmosphere – Petersaber Jan 30 '17 at 21:18
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    +1, but a link to some confirming source would be nice. – Ivan Kolmychek Jan 31 '17 at 08:26
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    @Petersaber if the ships are in orbit, destroying the ship would probably not make it fall back to the planet. Assuming it already was in stable orbit before the fight, you need to hit it with sufficient force to cause the ship to lower it's lower orbit point into the atmosphere. It probably will hit atmo only after approximately half an orbit. Even with fighters, who might fight on suborbital path (while still in space), a direct hit will not cause it to dramatically drop down, just slightly alter its parabolic path. Only while in atmo is power required to maintain course. – M'vy Jan 31 '17 at 09:24
  • @M'vy it was a battle in low orbit. I highly doubt they were in stable orbit (or any orbit for that matter). – Petersaber Jan 31 '17 at 10:51
  • @Petersaber If we're talking about battle cruisers, why wouldn't they be? It's illogical to think they are not in a stable orbit (or decaying orbit if you prefer) to start with. In that case, yes they would eventually fall back, but that'd take time. Unless we consider they are just hovering above a planet with no orbital speed, which would constantly require an immense amount of power. While it's science fiction, it does not make sense. Ships just tipping and falling back to planets after being hit shouldn't happen outside atmo. – M'vy Jan 31 '17 at 11:01
  • @M'vy I think their movement would be dictated by avoiding enemy fire and strategic formations, and not orbital mechanics (which would make their position predictible, and any strategist would take advantage of that). It's a space opera, not The Expanse. Anyway, they're in a very low orbit. Chances are they were actually hovering – Petersaber Jan 31 '17 at 14:28
  • @M'vy It's rather obvious that they are stationary high above the imperial palace - they are not in orbit, they are hovering. Once you lose station keeping, you drop - hard. If they were actually in orbit, they would have long since lost sight of the palace - but it seems that the battle has taken half an hour or so (including the "kidnapping") and they're still above the palace. Even the part of the battle we see is something like 10-15 minute, plenty of time to lose sight. Yet the ships don't seem to move at all against the planet, despite the great orbital velocities at such low height. – Luaan Jan 31 '17 at 15:32
  • @Luaan whatever, we're arguing on things that are not made to be argued with in the first place. We'd find a lot of contradictions and inexactitudes. – M'vy Jan 31 '17 at 15:40
  • @M'vy indeed. Star Wars isn't exactly known for being scientifically accurate – Petersaber Jan 31 '17 at 16:47
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If you watch the movie "Gravity", you get a better idea of what an explosion in space would really look like, plus the fact that there would be no sound. In addition, they more accurately depict that the shrapnel after the explosion would not simply be "floating" around like it is shown in most "Star Wars" like films, but would become orbital high speed projectiles creating secondary explosions when hitting anything else. The entire concept is a construct of the movie producers that flies in the face of reality... but that's not what we want to see in a movie like that!

JRaef
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  • While it's true that the shrapnel would be high-speed projectiles, so are the other ships in the scene and the camera as well. Since they're all more or less in the same orbit, their velocities relative to one another are fairly small. In Gravity, the shrapnel and the space shuttle were presumably on very different orbits and so they had very high velocities relative to one another. – Ben Sutton Jan 30 '17 at 23:03
  • Upvote. However, the relative velocities can range from very small to very, very large, depending on the orbits. Look at what happened when they blasted that Chinese satellite.. – SDsolar Jan 31 '17 at 00:44
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    Actually, shrapnel was one of the least realistic parts of Gravity. It behaved more like a strong water current that follows the heroine from higher to lower orbit, and then back to higher orbit (sic!) while adjusting the flow to hit the heroine as she moves north (or south) of the derbis' orbit. rather than a bunch of small debris. – Petersaber Jan 31 '17 at 08:32
  • @BenSutton They aren't even in orbit, actually - they're hovering above the city. That's why the ships start falling down when seriously damaged, and that's why they keep station above the imperial palace for half an hour. It's a space battle, but not an orbital battle. The debris would be dangerous for other craft (mainly the fighters - I assume it's trivial cobble to the capital ships with shields on), but it would quickly fall back to Coruscant and mostly burn up in the atmosphere. – Luaan Jan 31 '17 at 09:01
  • Remember that "Gravity" takes place in a universe where the Hubble, ISS, and Chinese space station are all a couple km away from each other at their closest points and moving in the same relative orbital direction and inclination, which they are definitely not in our universe. – Scott Whitlock May 14 '18 at 16:51
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Most (all?) of the ships discussed exhibit artificial gravity - people stand/sit/walk normally on board. This could cause the internal atmospheric oxygen to stay around for long enough for a explosion/fire to occur.

This could also be an integral part of the drive mechanism, which could account for ships falling to local gravity wells as soon as it is disabled, as they were not in an orbit, but rather hovering apart from deliberate movement.

Mark
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Yes, the atmosphere contributes, for sure. And remember that any metal that ends in "ium" will burn. Titanium, Magnesium, Aluminium, Sodium, Potassium, etc.

Just feed them a little oxygen and they will burn bright white.

SDsolar
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    The atmosphere of what? – Adamant Jan 30 '17 at 01:52
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    Aluminium doesn't burn bright white when you just add oxygen to it. You need a little more for that. It oxidates like crazy, yes, but that's usually without fire. At room temperature, that is. – Mast Jan 30 '17 at 08:27
  • Aluminum was the fuel for the space shuttle booster engines. As bright as magnesium and they didn't even use lasers to really pep it up. And yes, I forgot about unobtanium being the exception to the rule. ;-) Love the universal solvent bottle. Or lack thereof. As for atmosphere, how else would the carbon units survive? – SDsolar Jan 30 '17 at 10:42
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    @SDsolar I am explaining about battles in space, not in an atmosphere. – Count Dooku Jan 30 '17 at 11:06
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    @CountDooku The atomsphere in question, would be the one leaking from the ship. Atomsphere might have been a bad choice of word, but it's not entirely wrong. – Clearer Jan 30 '17 at 13:36
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    how do you keep the "little oxygen" near the chunks of magnesium? After one second the oxygen molecules will be a third of a mile away (the RMS speed of air molecules is 502 m/s at 20C) – RedGrittyBrick Jan 30 '17 at 16:19
  • @MichaelKjörling is there a ratio that can give SOMEWHAT an effect in the void and still preserve some of the scientifically inclined viewers' sanity? – Patrice Jan 30 '17 at 19:20
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    Vanadium, chromium, cadmium, osmium, iridium, indium and definitely try burning rhenium, that'll be fun. – Jeroen Mostert Jan 30 '17 at 19:47
  • Ha. That's great. Meanwhile, here is a good quiz for the technically-inclined viewer. Could you survive the Star Wars Universe? : http://www.csmonitor.com/The-Culture/Movies/2015/0504/Could-you-survive-the-Star-Wars-universe-Take-our-quiz/Your-commanding-officer-has-instructed-you-to-plug-the-thermal-exhaust-port-of-the-Death-Star – SDsolar Jan 31 '17 at 00:43
  • @Harlemme Decompression is usually depicted wrong too. In reality, it's something akin to a boat leak (a very low flow, not much of a wind - but still necessary to fix ASAP) or the fan favourite, explosive decompression - which last for just an instant. After all, that's why it's explosive - you can't keep a room's air rushing out at supersonic speeds for long. If you lose the wall of your room, all you get is a single brutal, short pop. It only works for serious space movies - in space drama like Star Wars, you're going to botch it up anyway. – Luaan Jan 31 '17 at 09:11
  • Almost every metal burns, if temperature, pressure and/or oxygen concentration match, including iron, copper, zinc, etc. There is no need to invent a suffix-based rule. – Holger Jan 31 '17 at 13:09
  • 'remember that any metal that ends in "ium" will burn' That's just nonsense. Either it's a over-specific tautology (essentially anything will burn if you heat it enough and oxidize it hard enough, so why restrict to some class of metals based on their name) or it's false (under "reasonable" conditions, for example, niobium is non-flammable unless ground to an extremely fine powder). – David Richerby Jan 31 '17 at 13:17
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The reason the ships burn in space is because the script writers didn't know anything about outer space. The fact that there's no air means once there is a hull breach, the explosive decompression will suck all the oxygen from the ship so where's the oxygen to fuel the fire? Yes, the fire could've started inside the ship, but the lack of air pressure would stop oxidation long before anything could explode, and I think that's what they missed. These days, they pay someone to edit movies for continuity, so I guess​ someone didn't do their homework.

Harlemme
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    As the accepted answer explains, you don't need oxygen for a fire. All you need is an oxidizer. Oxygen happens to be a good oxidizer (it's in the name and all), but it's certainly not the only one. Even in real life, fire in space is very much possible. Just not one fueled by quickly escaping oxygen (at least not for very long). It also does not follow that a hull breach would make an oxygen-fueled explosion impossible. On the contrary, the rapid flow of air could ignite sparks and fan flames that would have burned slower without it (assuming a relatively small breach). – Jeroen Mostert Jan 31 '17 at 11:36
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    As a side detail, air is blown from ships, not sucked. – ClickRick Jan 31 '17 at 13:53
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    What do you mean? I guess it's relative to your point of view, but if you're inside the ship, the air is being sucked out by the vacuum. Also, thanks for correcting me on the oxidation thing, although I still don't understand something can burn in space, unless we're speaking of solid fuels. Explode, yes. Burn, no. – Harlemme Feb 02 '17 at 05:42