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An Explosion in a Vacuum

  1. Sep 21, 2009 #1
    I was wondering if anyone knew what an explosion would look like in a vacuum? Theoretically lets say if something blew up in space. I was just curious because Hollywood sometimes still makes it look like an explosion on Earth but it should not be, right?
     
  2. jcsd
  3. Sep 21, 2009 #2

    berkeman

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    Depends on what's blowing up.
     
  4. Sep 21, 2009 #3
    Okay I think I see what you mean. Basically what I mean is, if it was a grenade or something equivalent?
     
  5. Sep 21, 2009 #4

    berkeman

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    Well, even in our atmosphere, a grenade just makes a loud noise. No giant flame ball, just shrapnel. And injured people. The flame balls come from flammable liquids and gasses, burning with O2 in the atmosphere.
     
  6. Sep 22, 2009 #5

    alxm

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    It wouldn't look like much. Many if not most explosions don't actually look like much. The first law of "movie explosions" says that explosions must always be accompanied by a giant fireball, but in reality that's usually not the case.

    As Berkeman says, when you do have a giant fireball, it's because something else is burning. For instance gasoline. When creating their explosions, film pyrotechnicians often use a small charge to disperse a bunch of flammable liquid which is simultaneously ignited - creating a big fireball but not actually a big explosion. Just add a nice sound effect and the audience gets what they want.

    So in short, I'd expect real explosions look pretty much the same, which isn't much. Except that they'll expand faster. A 'movie-type' explosion with a giant fireball isn't going to have a giant fireball though, since there's no oxygen for it to burn in. (this is not a problem for the explosives themselves, which contain their own oxidizer.)
     
  7. Sep 22, 2009 #6
    I think it's much the same except that it expands faster. If the explosion occurs in space, the debris must go in straight lines and forever unless captured by objects passing by.
     
  8. Aug 17, 2010 #7
    Ok. First, in the instance of a grenade, frag or High explosive, it would and could theoretically explode in a vacuum, however, it most definitely would not look like the movies or make any sound in space. Since it needs no outside sources of oxygen to explode, it would start of like a normal earthly explosive reaction. The effects of that reaction or the duration is under speculation here.

    I theorize that it would explode, however not have remotely the same effect as on Earth because of the chemical reaction after the initial explosion, shock wave (ie: expanding hot gasses), would not be affected by Earth's gravity and atmosphere.

    So in conclusion, a grenade explosion in space would look like a brief flash and an expanding ball of debris and maybe some sparks (heated metal debris). No fire ball, no sound, not even much smoke. The only poof if any you would see is the brief expansion of gasses given of by the initial reaction.

    If Hydrogen, Oxygen, nuclear, or other fuels explode, like on a space ship, I still have no clue about how it would look, but Id love to find out. (minus destroying a space ship of course:)
     
  9. Aug 17, 2010 #8
    At one time in the early 1960's (President Eisenhouer proclaimed a complete nuclear test ban in October 1958), nuclear weapons scientists were studying different ways of hiding nuclear weapons tests. One way was detonating a nuclear weapon in vacuum on the far side of the Moon. The test would be invisible because the debris, plasma, and x-rays would be shielded by the Moon. One likely observable would be electromagnetic radiation, and possible aurora borealis.

    In this biography of Edward Teller, "..... Under Teller' direction, his colleagues at Livermore devised ever wilder schemes to prove that nuclear testing could be hidden and, therefore, a test ban was not possible. These included exploding weapons in deep caves, building a gargantuan shield to hide x-rays from earthbound observers, and planning nuclear tests on the far side of the moon.

    See http://www.lewrockwell.com/orig5/wittner7.html [Broken]

    Some nuclear weapons tests were actually carried out by the United States and USSR above the atmosphere (up to 400 Km, in vacuum) in the late 1950's and early 1660's:

    http://en.wikipedia.org/wiki/High-altitude_nuclear_explosion

    Bob S
     
    Last edited by a moderator: May 4, 2017
  10. Aug 17, 2010 #9

    DaveC426913

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    A cool visual example of an explosion in space can be seen in the http://www.youtube.com/watch?v=Obd_jTO66-0".

    It looks for all the world like a explosion of glitter. (There's no smoke, just shiny particles flying off in fairly straight, ballistic trajectories.)

    Course, I don't know how much of that is propellant and how much is debris from explosive bolts. Once the Ascent Module has pulled away, there's no exhaust to be seen...
     
    Last edited by a moderator: Apr 25, 2017
  11. Aug 17, 2010 #10
    I've always wondered what it would "look" like, also. Especially a nuclear bomb, since it's alot of energy and, well...where does it go? I assume it's all pretty much light/ gamma rays, but still...I guess I'm not really sure what that means. What it would look/ feel like, what it would do to objects in proximity.

    I just played this game "Modern Warfare 2" and there's a scene where a nuclear bomb explodes in space, and takes out the international space station. I called BS on the way they made the explosion look...but, at the same time, I don't know.

    No articles I've found on the internet described it to my satisfaction.
     
  12. Aug 17, 2010 #11
  13. Aug 17, 2010 #12

    DaveC426913

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  14. Jan 23, 2012 #13
    Hey all, I just registered just to share this stuff here.

    If you are all interested in some visuals of how it would look like I would like to recommend you check out the best documentary I have ever seen on nukes.

    Trinity and Beyond
    http://en.wikipedia.org/wiki/Trinity_and_Beyond

    it's available in glorious crystal clear Blu Ray, and it has quite a bit of archival footage on nuke testing in space towards the latter half of the doc. You can actually see this section here I don't remember if it's all, I just skimmed it over - but check out the original in its entirety anyway.

    Peter Kuran also made a specifically dedicated documentary on nuke testing in space called "Nukes in Space" http://www.imdb.com/title/tt0206179/
     
    Last edited by a moderator: Sep 25, 2014
  15. Jan 23, 2012 #14

    sophiecentaur

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    Hollywood took a big step forward when they began filming explosions and rockets from underneath rather than from the side. At least the ejecta went in all directions equally. Watch the old Buck Rogers series. Unbelievable - sparks falling downwards and smoke drifting upwards. Doing the shots actually up in space would cost quite a bit more - but now there's CGI. Everything is believable.
     
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