cross-posted from: https://feddit.org/post/1104168
this post was submitted on 24 Jul 2024
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Any chance you know the canon explanation of how they counteract the gravity generated by the Deathstar's mass?
How much gravity would the Deathstar’s mass provide? I feel like it would be very small considering it has no real massive central solid or liquid core.
It's the size of a moon and made from metal: It's definitely generating some gravity (even a small amount of mass generates gravity) but I guess whatever tech they use to generate gravity overcomes it.
It's the size of a very, very small moon, and mostly hollow.
I should call her
Yeah the fact it's called a small moon is slightly deceptive to us because our moon is absolutely huge as far as moons go. The natives of the SW universe would be used to much much smaller moons.
For reference, our moon is 3475km across and the death star is 150km across, so it's diameter is 23 smaller. It's also weighed at about 900million tonnes or 9*10^14kg.
If I'm right (which I'm likely not). g=(GM)/r² or g=(6.66710^-119*10^13)/75².
That's a gravity of 1.086x10^-5m/s² or if I round with pure disrespect for physics, 100,000 times weaker than earth's gravity. Essentially it's totally negligible compared to their artificial gravity. Hell, I don't even think a marble on the floor would overcome it's own grip and roll towards the center of the space station.
My maths is almost certainly wrong somewhere here, I failed it badly.
Our moon is huge for a planet of Earth's size, but not compared to the big moons of Jupiter and Saturn.
Last time I looked it up, I used Pluto's moons as a reference because some of them are smaller than DS1, but Charon is quite a bit bigger. Based on the shapes of Pluto's moons, I think even if DS1 were solid it would still be too small to compact itself into a sphere with its own gravity.
Fun fact: Charon is even more huge relative to Pluto (just over 50% of Pluto's diameter) than Luna is compared to Earth (about 25% of Earth's diameter).
fun fact, pluto and charon are technically a binary planet(oid), because the point they orbit is in-between them. (Charon doesn't orbit Pluto, they both circle empty space)
For kids who like a movie reference to rely upon: https://media1.tenor.com/m/jl-z-8otCc0AAAAC/titanic-weee.gif
Pluto has more than one satellite?
It has five that we know of.
Must have missed that. Cool!
So small that a natural body of that size probably wouldn't be massive enough to hold a spherical shape. DS1 was a little smaller than the real asteroid 128 Nemesis, which isn't spherical. Maybe if it were made of something extremely dense, it would be, but you're not likely to find a natural spherical object that size.
Now that I think of it, this puts the "that's no moon" scene in perspective. Luke is a country bumpkin who just calls it a moon, but Obi-wan has an idea of its size (perhaps from glancing at the Falcon's scans, since size and distance is hard to judge by eye; or he's just a space wizard), and knows a natural object couldn't be that spherical.
Unless the object formed as a sphere of molten water in the vacuum goldilocks zone, then froze into an huge sphere of ice as the star cooled.
It wouldn't need to generate gravity.
Acceleration "down" would be enough.
Only if it was undergoing constant acceleration, which we know it to be incapable of.
It’s got sublight thrusters and steering doesn’t it? It could just fly around and around a circular path.
I ran the numbers, and it says about 0.00473m^2^2
The gravity is negligible. The official sizes of the Death Stars have been 120 - 900 km in diameter according to rebel scale. For comparison, Earths moon is ≈3500~~0~~ km in Idiameter, and its gravity is 1/6 of earth’s. On top of that, the Death Stars are mostly hallow, being a metal framework, instead of solid rock.
Our Death Star, who art in heaven,
Hallowed be thy name,
Thy empire come, thy will be done,
On Alderaan as it is in heaven,
Give us this day our daily rations,
And forgive us our rebellion,
As we forgive those who rebel against us,
And lead us not to the light side,
But deliver us from the Jedi,
For thine is the empire, and the unlimited power, and the dark side forever,
Amen
If Lemmy had gold, I'd give it to you.
Off the a factor of 10. The Moon has a diameter of almost 3500 km (Earth's circumference is about 40,000 km, so your diameter would make the Moon larger than Earth).
However, the Death Star being mostly filled with air still means you're probably right about gravity being negligible.
Whoops. Good catch! so about 4-30 times the size of the Death Star. That would mean the gravity of the Death Star is at most 1/24th that of earth’s, if it were solid rock and my math is correct. That’s at the surface, though. As you go inside, gravity will decrease until you reach the center where there will be no gravity at all because all the mass of the space station is pulling you away from the center equally. (assuming a uniform mass distribution).
g ≈ M/r^2
V ≈ r^3.
uniform density: ρ for simplicity’s sake
M = ρV
—> g ≈ ρr where r is the distance from the center of the death star, but no further than the surface
It’s not massive enough to create its own gravity. They use gravity deck plating.
Even if it was massive enough, if they can keep people sticking to the ground in a tiny ship they can surely counteract the gravity of a space station.
Also, most of their spaceships have wings. We're thinking about this way too hard.
They don't all have wings. Only the X-Wing and Imperial transport ships have actual wings, and we've seen them fly through atmospheres.
Well, yeah, but we've also seen the ones that look like a hamburger patty fly through the atmosphere (and, in fact, outmaneouver the winged ones). Clearly that's not what they're for.
Ah yeah. Dang. Well there probably a good technical reason behind it. I'm no starship engineer in the Star Wars universe.
The hamburger was originally a cargo ship, the one we see is special in that it has a bunch of very expensive, very powerful engines added.
It's no wonder that a street racer can outpace army jeeps. Also, they couldn't outpace TIE fighters in Ep.IV, which are known for being very fast for a coffee table.
I think the usual in universe reasoning is heat dissipation.
They are clearly not wings meant to create aerodinamic lift.
Well, no, they're meant to make the pew-pew laser fights look like a film about airplane dogfights. So yeah, way overthinking it.
You’re here discussing it too, man
Oh, yeah, no, but that's because I'm a nerd.
Technically everything with mass creates its own gravitational field; most things just aren't massive enough for it to be detectable.
One of my favorite science facts: Because of how the strength of gravity diminishes as you get further away and stronger as you get closer, when you approach to within arms length of another person (approx 1m) the gravitational attraction between the two masses of your bodies can exceed the gravitational attraction between your body and the sun at any given time.
When the inverse square law and weak gravitational forces meet
Where I end and you begin
Another fun property of the inverse square law is that an infinite sheet of mass produces a gravitational field that is equally strong no matter how far you are from it.
It applies to any form of flux, like sound amplitude or light intensity.
This is why when you’re sitting on top of Mount Sanitas, you can hear traffic sounds at seemingly full volume. It’s just all the traffic of Boulder, which is roughly like an infinite sheet below you.
This is despite being unable to hear any given car more than a couple blocks away.
It’s also why if Superman flies over manhattan at night, he’s lit from underneath with an amount of light similar to someone who’s 10 feet from a skyscraper.
Yeah, but no one can escape the gravitational field of your mom.
(Sorry, couldn't resist, as I half expected your comment to end with a "your mom" joke)
“Gravity deck plating”… okay that makes sense. So basically each floor has its own gravity generation to orient you to it. They’re all placed “bottom to top” to work like a building but it’d be possible to put one in at a 90-degree angle for say maintenance work.
Like in the Falcon
There are crew walkways (I think they even have handguards!) along the beam path of the superlaser, so there are definitely at least a few small decks at different angles.
Artificial gravity and inertial compensators are pervasive (if relatively handwaved/unexplained) in the SW universe
Hoverpads have fully replaced wheels and datapads have fully replaced paper, even in the poorest most remote communities.