What evidence do you have that Yavin 4 is much closer to Yavin than the Moon is to Earth? I'm genuinely curious, I've never read the novelisations so if it's mentioned there I would be unaware of it.
yavin is slightly smaller, about 10,000km diameter, than earths 12,000km diameter. compare this shot
with this shot
we know that the squadron traveled approximately 200,000km from yavin 4 to intercept the DS. the moon, at its closest point to earth, is about 350,000km from earth. yavin is in the background on our left, the characters right. at that distance, they have already traveled most of the distance to the DS. does that look like 350,000km to you?
And yes, it almost certainly does have an effect. Probably a similar effect that the Moon has on Earth re tides and such. It evidently does not have an effect on surface gravity and all things related to it, since we see it to be a perfectly habitable Earth-like envionment.
true. it would seem to me to be a bit more pronounced, but I'm not an expert on these things.
Ok, that's a source for the number, thank you. Gas giants having higher surface gravity than Earth is perfectly true - and I never said otherwise, so I'm not sure why you bring it up. The point stands that with gas giants size does not automatically equate to mass. Case in point, Saturn has a mass slightly under 1/3 that of Jupiter, but has a mean diameter barely 20,000 km smaller than Jupiter (to be precise, Jupiter mean diameter, 138,000km, Saturn mean diameter, 114,000km). This is partly why Saturn's mean density is about half that of Jupiter - a simple size comparison tells you very little about gas giant planets.
true. I was just surmising that since most gas giants have increased gravity compared to earth, that yavin would be similar.
Yavin won't have much of an impact on the accelerations or velocities needed - anything taking off from Yavin 4 is already in orbit around Yavin by virtue of starting on the moon, which is in orbit. This is why stuff launching from Earth doesn't need to gain ~30km/s of velocity to stay in orbit around the Sun, it already has that velocity from Earth.
would yavins gravity not affect the squadrons orbital path though? if the DS is in a lower orbit like you said, could they not use the gravity to accelerate instead of using up their fuel? like I said, I'm not an expert. thats why I ask the, as some would see them, dumb questions.
That I am fully aware of, I just dislike the expression as it implies physics or parts thereof are subject to belief in them working when this is manifestly not true.
I guess I did phrase that kind of weird.
On the larger orbital mechanics question, I'm rather interested now. The fighters take off from a moon in a stable orbit. The DS is explicitly said to be orbiting Yavin (voice chatter on the bridge "we are preparing to orbit the planet") and catches up to the moon (or at least to a firing position) quite rapidly. Logically, the DS would be in a lower orbit with a shorter duration. So the fighters have to take off, shed velocity to lower their orbit, close on the DS (or intercept at any rate) and then slow to relative rest with the DS to do battle. That then can do that and a return trip, plus extensive dogfighting, on one fuel load is impressive indeed.
aside from using the gravity like I said above, there are other quotes that have to do with speed/acceleration. like red leader stating "accelerate to attack speed" after they get through the magnetic field. or luke stating "we're going in, we're going in full throttle. that ought to keep those fighters off our backs." if we take quotes at face value, then it would definitely take a lot longer than 5 minutes to make the trip from yavin 4 to the IP with the DS. after all, at full throttle, it took luke over 3 minutes to fire at the exhaust port. with a diameter of 120km, that gives a circumference of 377km. divide that by 180 and you get a maximum of 2.09kps average speed. thats part of the reason that I question wongs "5 minutes from yavin 4 to the DS". it seems to me that he didn't take into account the fact that we see ships taking off, then the scene cuts to the nav table and the 15 minute to firing range call, then to the squadron most of the way to the DS. time is very compressed in the star wars films. how long from the time they took off to the time that the 15 minute call was made? in the current version of the film, that take off scene was leisurely and slow. with me so far?