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As we discussed it in this question, the Death Star can deliver a mind-boggling amount of energy. If it is capable of blowing up an Earth-sized planet, this means the equivalent of the annihilation energy of over 1,200,000,000,000 tonnes of antimatter. In comparison, nukes measure on this scale in the gram range (the one used at Hiroshima being under one gram). This means, even if the shot gets a million times weaker due to distance, it is probably still enough to kill all multi-cellular life on a planet.

Regarding this, how much is the maximum effective range of the Death Star? By effective I mean that even if it does not blow up a planet Alderaan-style, it delivers enough damage on a planetary scale to effectively cripple a planet.

Is there any related information in the expanded universe?

DavidW
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vsz
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    Lasers cannot blow up planets. The weapon they are using is not a laser. Lasers cannot create antimatter from matter. It would need to be a particle weapon that is made from antimatter, directed at a planet, annihilating the planet upon contact and creating new antimatter so the entire planet is destroyed. Otherwise the rubble from the explosion would destroy the Death Star as well... – Thaddeus Howze Jul 08 '12 at 23:52
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    @Thaddeus: I didn't say it was a laser, Kevin edited it in. – vsz Jul 09 '12 at 03:10
  • This is a physics question, assuming that it is a plain laser. I know a flashlight behaves according to square inverse, but I'm not so sure how lasers behave... even with square inverse, it's going to have to be more than a few AUs before I'd want to be in the crosshairs. – John O Jul 09 '12 at 16:28
  • Theoretically, wouldn't a blast of plasma continue through a vacuum for an infinite amount of distance without losing any strength? It should only lose cohesion upon contact with other matter... – Omegacron Apr 24 '15 at 17:07

2 Answers2

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For my understanding, the effective range should essentially be several AU. Considering the main weapon is a laser, its effectiveness won't degrade with distance other than losing its concentration (like a laser pointer or flashlight: the further away the target spot is, the bigger the area being lighted). We don't know how focused it is (i.e. how much power is lost over a given distance).

According to this discussion, the Technical Journal of the Imperial Forces states the effective range of the superlaser is said to be about 157 lightseconds, which is something like 47 million kilometers (29 million miles) or 0.3 AU (a third of Earth's orbit). Although I don't know how this effectiveness is defined (just destroy everything living on the surface vs. destroy the surface vs. blow up the whole planet). If the station is able to destroy a planet at that distance, the whole setting from the movie sounds a bit absurd, considering they risked getting hit by debris, while they could have stayed away a lot further.

DavidW
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Mario
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    If it is actually just a laser, keep in mind that a laser is only effectively "focused" for a brief distance. The practical distance of the Death Star is likely optimized for some distance limited by the geometry of the focal array. – Gorchestopher H Jul 09 '12 at 02:38
  • @Gorchestopher H: Still, a billion times less energy is enough to cripple a planet. This means the range could have theoretically be increased by several orders of magnitude, and still be dangerous on a planetary scale. Energy required to blow up a planet > 1000000000 * energy required to kill everyone on its surface. – vsz Jul 09 '12 at 03:12
  • @vsz The limitation would still be the focus if it was a laser. Divergence continues on. – Gorchestopher H Jul 09 '12 at 11:32
  • @Gorchestopher H: Yes, but very slowly. If it can blow up a planet at 1AU, it will probably not be completely harmless at 2AU. Or at 100AU. – vsz Jul 09 '12 at 14:06
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    @Chad: Do you have a source about the antimatter stream? – vsz Jul 09 '12 at 14:07
  • There isn't a canon article but lasers no matter how powerful cannot create ANTIMATTER from matter. Call it whatever you like but it ISN'T a laser. – Thaddeus Howze Jul 09 '12 at 14:13
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    @Thaddeus: Ok, but this still not proves, and not even suggests that antimatter is involved in any form in the Death Star's weapon. – vsz Jul 09 '12 at 14:28
  • Planets are incredibly massive and held together by gravitational forces. To cause a planet to explode, especially one the size of Earth could only be done by converting a portion of the planet to antimatter. 1 kg of antimatter is yields 43 kilotons of TNT. Only antimatter has the yield needed to destroy planets. No conventional nuclear explosion could overcome the forces of gravity to cause a planet to disperse as cleanly and effectively as the Death Star weapon did. Hollywood has distorted science. Planets are very difficult to blow up. Killing all life? Easy as pie. – Thaddeus Howze Jul 09 '12 at 14:49
  • When has been the last time you flew your Millenium Falcon to the next supermarket to buy some groceries? :P – Mario Jul 09 '12 at 17:34
  • Missed the edit window: Or in other words: It's science FICTION after all. If you don't like the idea of it being a laser (I don't know of any source stating something else out of my mind), then you should also consider that their other weapons are no lasers, cause a laser wouldn't show up as a line flying through space (if you're fast enough, it would, but it wouldn't shine in all directions, therefore being invisible unless you're the target). – Mario Jul 09 '12 at 17:40
  • The Technical Journal has it listed as a particle beam weapon. While called a super laser it is like calling a motorcycle a bicycle because they both have 2 wheels. They may look somewhat alike the power for them is completely different. Wookiepedia calls it exotic matter beams – Chad Jul 09 '12 at 18:34
  • Unless this particle beam leaks into Hyperspace, its range should be several orders of magnitudes larger. Maybe it does leak into hyperspace, following the description given on Wookipedia (as it uses hyperspace to get most of the energy, and as it leaves singularities behind). Sadly, it does not cite any sources for that. – vsz Jul 09 '12 at 19:21
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From Wookieepedia:

The power of the first Death Star's superlaser was estimated to have been more than 2.4×10^32 watts, with an optimum range of 2,000,000 kilometers and a working range of 420,000,000 kilometers. Powerful enough to destroy a terrestrial planet, it was the most powerful energy weapon ever built at the time

And while the original source is not linked on Wookieepedia I believe this is from The Essential Guide to Weapons and Technology, it may also have been the Death Star Technical Companion.

DavidW
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  • Strange, that's less than 3 AU. Well, it's still much more than the range it was used in the movies (less than 0.01 AU). – vsz Jul 09 '12 at 18:57
  • @vsz because it is not a lazer despite what it is called. It is a exotic matter beam... I am not sure how that compares to antimatter but based on its output I am guessing favorably on the side of destructive power. – Chad Jul 09 '12 at 19:00
  • Even if it's a particle beam, there is no friction in space (at least not at such a small distance). As even a billionth of that energy is devastating, this should not limit the range that much. Or, maybe it starts "leaking" into Hyperspace, that's the cause of such a short range? – vsz Jul 09 '12 at 19:17
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    @vzz - Contrary to popular belief space is not empty just sparse. There is lots of dust, debris, and hydrogen it is just so diffuse as to seem empty. But over long distances those little particles would siphon off significant power. – Chad Jul 09 '12 at 19:23
  • Also consider it getting harder to hit targets further away, as you'll have to include their trajectory as well as your own. At some distance your aiming might simply be not good enough anymore to ensure a hit at all (it might take some time to do the calculations, but you have to aim properly as well). – Mario Jul 09 '12 at 21:08
  • @Chad: I know, this is why I wrote "at least not at such a small distance". Over a few hundred thousand km it's insignificant. If we are talking about light-years, yes. – vsz Jul 10 '12 at 04:55
  • @Mario: that aiming, and the predicting of the orbit of a planet are possible even today, at least across a few AU or maybe more. – vsz Jul 10 '12 at 04:56
  • You misunderstood me. The aiming (the math part) is possible, sure. But the further your target is away, the smaller the margins for the aiming are. At some point you might need such a precise orientation, that you're simply no longer able to guarantee it due to thrusters or whatever not being precise enough. Imaging shooting at a targeting range - at 3 ft, aiming in the approximate direction is more than enough - but at 300 ft you better have very steady aiming and stuff. – Mario Jul 10 '12 at 07:41
  • @vsz - I know this is exotic matter but... antimatter has a strong attraction towards matter. So assuming this exotic matter has similar properties it is not just the particles directly in the path but any near enough to be affected. In addition we are talking hundreds of millions of km not thousands – Chad Jul 10 '12 at 12:49
  • @Mario You do not need to be accurate with an antimatter beam get it near and the natural attraction towards matter should correct. You do not need to hit a specific city with a planet buster either. Just hit it somewhere. – Chad Jul 10 '12 at 12:51
  • I suspect Wookiepedia's original source was the WEG SWRPG supplement Death Star Technical Companion. – aramis Jul 11 '12 at 00:03
  • Let's assume that conservation of energy still holds. Taking the power above (a quite useless piece of data, energy of a pulse is what we need), assuming no focusing at all (a point source, losing most of energy into space), to vaporize 1m of water over the entire planet in one millisecond (if we had joules, we wouldn't have to assume duration), you'd need to be 0.01AU away. That's without any focusing. With beam width of 1° (still worse than laser pointer), it's about 3AU. That's for vaporising everything that moves on the surface. – orion Jan 07 '16 at 21:24