Death Star Physics

[Beor]

Okay, I know that this is Star Wars we're talking about here, but still. I was having a converstaion with one of my buddies here about gravity, and what not, and the converstion ended up passing into the realm of Star Wars, and whether or not the Death Star would have gravity or not. We started arguing it, and I know it would have to, because all mass creates or whatever a little bit of gravity, and the Death Star is massive enough that I would imagine it would put a big enough dent in the fabric of space to have a substanial gravitational field. Now, I know that in Star Wars on the Death Star, there seems to be a definite traditional "down", as if the core or whatever pulls objects towards the southern end of the space station, rather than just relying on or amplifying the gravity already there that would pull objects towards the core. Anyway, there is a lot to be discussed and debated, if anyone is interested. If this thread has already been posted in some shape or form, I apologize, but it seemed like a matter worthy of discussion.

[Earniel]

Judging by the scenes in the Death Star it definitely has artificial gravity but I never thought much about how it was acchieved. I believe TB has got a thread about creating artificial gravity somewhere in this forum.

[Valandil]

Beor is right that gravity is associated with mass - it's an inherent property of mass. So - the Death Star would have whatever gravitational field would be associated with any object of the same mass.

Let's don't confuse that with volume though. Even if it was as large as some moons, it was not solid throughout. It was a essentially a ship - so it was hollow. I doubt it had near the mass of a planetary body of the same diameter.

On the inside, a gravitational field would be very helpful. I think we can safely put that in the category of "artificial gravity" - some technology to supplement whatever natural gravity the Death Star itself would have. There may have even been sections where this was not applied - so that there was a near weightless state, and you could "float" around (this might be helpful in some service areas??).

[Farimir Captain of Gondor]

Originally Posted by Valandil

Beor is right that gravity is associated with mass - it's an inherent property of mass. So - the Death Star would have whatever gravitational field would be associated with any object of the same mass.

Let's don't confuse that with volume though. Even if it was as large as some moons, it was not solid throughout. It was a essentially a ship - so it was hollow. I doubt it had near the mass of a planetary body of the same diameter.

So if an object of smaller size and consisted of less mass floated by the Death Star it wouldn't be pulled into it?

[Valandil]

It depends on how close it passed, what velocity (both speed and direction) the two objects were moving, relative to one another - and the total mass of each of the two objects.

The gravitational attraction is actually the attraction of two masses to one another. You experience gravity because of how your mass interacts with the mass of the earth. There's a Newtonian equation, I think...

In short though - yes, a passing object could be pulled into (or into orbit around) the Death Star. However - this is something they would have anticipated as happening all the time - so the DS was likely equipped with some kind of deflectors to repulse such objects away. I don't think they would want the thing to be constantly pelted with space dust and so forth. Especially when it's purpose was to MAKE planetary fragments!

[Beor]

Exactly. Einstein has some pretty good illustrations as to a sort of easy way to see how gravity is. He paints space almost like a sheet stretched taut, and a massive object, say a planet or a star, would be like a marble on the sheet, it would create an indent that smaller particles would fall into. For instance, a bowling ball, if placed in the middle of the sheet, would create a very large distortion in the sheet, and if one were to roll a marble past it, the marble would incline towards the bowling ball and eventually hit it. Now, we dont fly into the sun, because all the planets give off their own gravity, due to their having mass. So, at the same time the sun pulls us in, the other planets are pulling us out, mainly Jupiter, if I remember correctly. That, and I believe there is some bit of centrufugal motion in there too.

I understand that the Death Star's gravity would be low, due, like Val said, to the fact that it is indeed a ship, but the gravity is there. Anyone ever read into the String Theory at all?

[Valandil]

Actually - the other planets' gravitation does not affect us - as far as I know.

What keeps us in orbit is the balance between our gravitational attraction with the sun and the lateral motion that we have from the sun.

[Beor]

I know that the other planet's gravitation affects us, though how much could be debateable, or researched, if I had the time, but it has to affect us a little bit, maybe not so much as I said, but I know its there.

And yes, the fact that we spin around the sun does fight against the suns gravitational pull.

I think maybe the other planets graviational fields, mainly Jupiter, may have had more of an effect on earth when the solar system was forming than they do now, but dont quote me.

[mithrand1r]

Originally Posted by Beor

I know that the other planet's gravitation affects us, though how much could be debateable, or researched, if I had the time, but it has to affect us a little bit, maybe not so much as I said, but I know its there.

And yes, the fact that we spin around the sun does fight against the suns gravitational pull.

I think maybe the other planets graviational fields, mainly Jupiter, may have had more of an effect on earth when the solar system was forming than they do now, but dont quote me.

I think the gravity of Sun and the Moon have the greatest effect on the Earth compared to other objects in the Solar System. The Sun due to its relatively huge mass and the Moon due to its proximity to the Earth.

The next in ranking would be (surpise, surprise) Venus, but its effect on the Earth is very tiny when compared to the Sun and the Moon.

Some links below on this topic. Enjoy

http://amazing-space.stsci.edu/resou...apture,gravity,

2. What factors determine the force of gravity between two bodies?

The force of gravity (F) depends on the masses of the two bodies (m1, m2) and the distance between the bodies' centers (r). There is a direct proportion between mass and gravitational force: If you double the mass of one body, the gravitational force between them is also doubled. The gravitational force is inversely proportional to the square of the distance: If you double the distance between the two bodies, the force of gravity is reduced to one-fourth its original value.

The equation relating these ideas is: F = G(m1m2)/r2, where G is the universal gravitational constant equal to 6.67 x 10-11 Nm2/kg2 or m3/s2kg).

http://science.nasa.gov/headlines/y2000/ast04may_1m.htm

Maximum Tidal Forces of the Sun, Moon, and Planets on the Earth Solar System Object Tidal Force
___Moon = 2.1
____Sun = 1.00
__Venus = 0.000113
Jupiter = 0.0000131
___Mars = 0.0000023
Mercury = 0.0000007
_Saturn = 0.0000005
_Uranus = 0.000000001
Neptune = 0.000000002
__Pluto = 0.0000000000001

Above: In this table, adapted from the Griffith Observatory's "Planetary Alignments in 2000", the Sun exerts 1 unit of tidal force on the Earth; the Moon has a little more than twice the effect of the Sun; the other nine planets together with all their moons add only another one five-thousandth as much.

That's not to say that Jupiter isn't a powerful source of tides in its vicinity. You just have to be nearby to feel them. The innermost of Jupiter's big moons, Io, experiences tidal forces nearly 20,000 times stronger than the forces we feel here on Earth due to the Moon. Solid tidal bulges on Io are about 100m high, taller than a 40-story building! This stretching triggers some of the most active volcanoes in the solar system. (See, e.g., Jupiter's Terrible Tides).

[Earniel]

Originally Posted by mithrand1r

The next in ranking would be (surpise, surprise) Venus, but its effect on the Earth is very tiny when compared to the Sun and the Moon.

Funny, I always assumed the next would be Jupiter because I once read that Jupiter's gravitational field works as a giant vacuumcleaner and draws many of the asteroids away that otherwise would have made Earth look like the moon.

[Jonathan]

Originally Posted by Eärniel

Funny, I always assumed the next would be Jupiter because I once read that Jupiter's gravitational field works as a giant vacuumcleaner and draws many of the asteroids away that otherwise would have made Earth look like the moon.

That is true. Indirectly, Jupiter's gravitation has a greater effect on earth than does Venus. However I've read that the tidal influences of Venus are bigger than those of Jupiter. The effects on the earth's tides are too small to be observable, but as for direct gravitational influence, Venus is ahead of Jupiter.

[mithrand1r]

Originally Posted by Eärniel

Funny, I always assumed the next would be Jupiter because I once read that Jupiter's gravitational field works as a giant vacuumcleaner and draws many of the asteroids away that otherwise would have made Earth look like the moon.

Fortunately we are not near that vacuum cleaner. That would really suck.

A big reason (for Venus Having a stronger effect on the Earth than Jupiter) is that Jupiter is much further from the Earth than Venus.

If you double the distance between two objects, the affect of gravity on each other is reduce to (1/4 or 25%) of what it was before.

The closest that Jupiter can be to the earth is about 391 million miles (Dist. from Sun in Millions of Miles: 484-93)
The closest that Venus can be to the earth is about 26 million miles (Dist. from Sun in Millions of Miles: 93-67)

391/26= about 15

That means (If I understand the idea about gravity correctly ) if the gravity of Venus and Jupiter were equal, the effect of Jupiter's gravity on the Earth would be about 240-250 times weaker than Venus' gravity on the Earth, due to distance alone.

Since Jupiter's gravity (effect on the Earth) is only about 1/11th of Venus' it gives one an idea of how much stronger Jupiter's gravity is than Venus' (or the Earth's for that matter since Venus and Earth are similar in size and density.)