Why didn't the Death Star just fire THROUGH the Yavin gas giant?

I have always been troubled by this...At the end of A New Hope, why couldn't the Death Star have merely fired the superlaser at the gas giant instead of waiting to go around it? If the gas giant is just a giant ball of gas, the superlaser would go right through it and still destroy Yavin IV where the rebels were, if there was a center core to the gas giant, it would be destroyed...which would cause a catastrophe, blowing up the gas giant would also probably destroy the moon based on the shockwaves, etc. Maybe not the entire planet, but it seems that it would at least totally lay waste to the surface, accomplishing the goal.

I just don't totally understand the logic...why bother taking the time to go around the gas giant, when you can simply fire your weapon through it or at it, and accomplish the same thing you were intending all along, the destruction of the Yavin IV rebel base?

 

gas + laser fire = explosion = end of death star?

 

There's no guarantee the superlaser shot would've penetrated through the gas giant and hit Yavin 4. They needed a precise, direct aim.

 

That'd be my guess. Davi, you yourself just said there would be a shock wave that would probably destroy the moon. If it destroyed a moon, then obviously it would destroy something the size of a small moon.

 

Yea, it's a simple matter of chemistry.

 

The superlaser took a long time to recharge and so Tarkin didn't want to miss. That was a possibility if they couldn't target the moon properly. Tarkin didn't think the rebels had a chance of damaging the station and so he took the time to get a proper lock on the target. An extra 30 minutes of no consequence to him given the alternative. He may also have wanted the satisfaction of seeing the rebels be destroyed and so waited for a proper shot.

 

Well a gas giant may be just a bunch of gas, but you've got to take into consideration that it's not just a ball of loose gas floating around in space. The deeper you get into the the more pressure there is, so at some point the gas is compressed to the point that it's almost a liquid. It also has extreme temperatures at this point as well. I highly doubt the blast would go through it, or possibly even destroy it (that's assuming the death star is even powerful enough to do this or, even designed to). I'm sure it would mess it up big time, regardless.

However, you may have a point in that by doing this it would cause major reprecussions to the orbit and climate of the moon. Then also, being that gas giants are so massive, they tend to affect the orbit of many other planets in the system, which the Empire may not wanted to have disrupted.

 

well, wouldn't survivability/escapability from shockwaves have already gone into the design of the Death Star? If it can't tolerate the shockwave from destroying planets, or be able to escape them, its a pretty useless superweapon. Logically, they would have to have a way to either absorb or escape the forces involved in the destruction of a planet. So, they must have some means to not get destroyed in the aftermath.

They couldn't have been too concerned with the rest of the Yavin system, as they were going to blow up Yavin IV anyway, without any regard to the effects it would have elsewhere, in much the same way they didn't care when they destroyed Alderaan. Given Alderaan and their intent to destroy Yavin IV, which would have had its own repercussions on the orbit of the gas giant, I don't think any case can be made that the Empire cared one way or the other about what happens to the rest of the system, so I don't think that would have been a consideration.

 

Yavin Prime was the gas giant which has like 20 something moons around it, one of which is Yavin IV. There were two other planets in the system though besides Yavin Prime.

 

If you have ever taken a look at calculations of the firepower for the DS superlaser[the tech Commentaries being one example] you will notice a phrase called "gravitational binding energy". This is the minimum amount of energy needed to make a given world come apart and not eventually form back into what would be a lifeless orb. For the Earth that number is 10^32 joules. If Alderaan is Earth sized then superlaser dished out 10^38 joules to make it explode like it did. Yavin may be approx the same size a our own Jupiter. Jupiter's gravitational binding energy needs 10^38 joules to be overcome, just the amount the DS dished out.
The break up would have been far slower and would have given the Rebels more time to evacuate before the mass of Yavin would have reached them. By orbiting the planet they cut down the needed time they would have needed to get away. I am not sure if a bolt of 10^38 joules could have gone through the core of such a world. Under such pressure a gas giant like Jupiter may have a core the size of Earth with the density of diamond. It's not the mass or the density alone, it's the combination of the two that may prevent a clear shot through Yavin.

 

How could the Death Star target the moon? They would be guessing at where to aim.

 

The same way we keep track of where the planets and moons are in our very own solar system, the Republic turned Empire will be interested in where things are when they come in from hyperspace. That begs the question of why didn't they just enter normal space a bit closer so they didn't have to orbit Yavin. Aside from the obvious need of drama it could be the requirement of having a lesser gravity field to deal with when leaving hyperspace.

Or, they enter the system and scan for the moon and do not see it. So they know it is on the other side. In the same way we can deduce the mass and orbit of a planet around another star via the tug of war between world and star a quick measurment taken of Yavin wuld tell them where the moon is. Also, they could have just launch probes for a quick peek.

I suppose too tht if you have FTL trvel you can leave satellites behind that constantly monitor the system so when you arrive you can glean info from them on where everything is. The Rebels trying to hide though would make those things there first targets if not by outright removal then by hacking into them to provide false info. However such things are done the DS could have come in thinking they were on the correct side to blow the moon away but wound up on the wrong side because of some misinformation by the Rebels. I imagne there is no EU on this matter.

 

What I meant is that they wouldn't be able to actually SEE the moon if Yavin was between them. How do you target something you can't see?

 

If not by direct picture via probes then by deducing a location via orbital disturbances. And who knows, it is possible that the scanners they use can peer through worlds in some fashion.

 

Sensors don't rely on visual information. They can detect the moon by its gravitic influence or by lots of other factors.

 

^^Thank you... I was almost about to spout out some Star Trek geekdom.

 

That's why submarines will never work!



Great post, VadersLaMent. I was going to say something about the theories regarding the core of gas giants like Jupiter, but you covered it for me.

 

Because it doesnt work that way.

Any number of outcomes could have befallen a decision like that. Theres a good chance they would've hit the rocky iron core of Yavin, among other unfortunate(for them) possibilities.
Theres also the rather massive magnetosphere, that could severely alter the laser's trajectery, along with gravitational pull, and superheated internal structure of a Gas Giant that would almost garauntee that that laser will not meet the target, even if they had technology that could locate the exact location of the moon, which they might have had, it WAS the Death Star afterall.

 

Well, I must have missed the meeting where they handed out the blueprints for the Death Star. I thank you all for teaching me how the targeting system works.

 

What would happen to a gas giant if they fired a superlaser into it anyhow? Would it blow up the core? Would the dense atmosphere just absorb the energy? Or would all the hydrogen and whatever else is in there just ignite and turn the thing into a blazing inferno?

 

Ditto, and how could they be sure that the makeup of that super laser beam wouldn't react with the type of gasses contained in the gas giant to some adverse effect? But I say mostly it would have caused a huge explosion, thus destroying the death star in the process

 

If Yavin is the size of Jupiter then the DS laser has just enough energy to break up the planet. It would be much less dramatic than the Alderaan explosion. It would be slower, perhaps taking hours or days. It would probably resemble an expansion rather than an explosion then disapait.

You can actually get this kind of power from large, blue O class stars which can emit 80,000 times the energy our own Sun does(this would equal Earth's minimum break up energy, not Jupiter's). Make yourself a dyson swarm to collect all that power and you too can have your very own superlaser. If wormholes are allowed by the Universe and are not just a mathmatical idea then such a power level might allow for opening up wormholes with a few seconds of power then shooting a laser through it to a target on the other side of the galaxy. Our Sun outputs 10^32 joules over a period of a few days or so where the O class blue stars do that in seconds.

let's review:

10^32 joules of energy is the minimum needed to break up the Earth; this is equal to the Sun's output in days, and an O class star's energy in seconds.
10^32 joules is needed to equal what the DS did to Alderaan, which may be Earth-sized, which is also the minimum energy needed to break up Jupiter, which also equals the power output of 100 billion stars(a galaxy) in one second.
The minimum energy needed to break up the Sun is approx 10^41 joules. A DS shot to the Sun would not break it up, but might turn it into a variable star which would be bad for the solar system.

Some scale, output approx in joules:

Lightnign bolt: 10^9
The Mother Of All Bombs: 10^10
The Nagasaki nuclear bomb: 10^13
The 50 megaton Tzar bomb: 10^17
Annual energy production on the Earth: 10^19


Orders of magnitude(energy)

 

It's only a model. (Shhhhh!)

 

To me, the planet is probably about 300 times larger than a planet capable of supporting life. The death star probably didn't have enough power to blow up a planet that size.

 

I'd agree with that..