this post was submitted on 24 Jul 2024
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Science Memes

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cross-posted from: https://feddit.org/post/1104168

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[–] [email protected] 74 points 5 months ago (2 children)

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.

[–] _haha_oh_wow_ 25 points 5 months ago (2 children)

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.

[–] [email protected] 68 points 5 months ago (3 children)

It's the size of a very, very small moon, and mostly hollow.

[–] [email protected] 47 points 5 months ago

I should call her

[–] [email protected] 33 points 5 months ago (2 children)

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.

[–] [email protected] 9 points 5 months ago (2 children)

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).

[–] [email protected] 5 points 5 months ago (1 children)

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)

[–] [email protected] 4 points 5 months ago* (last edited 5 months ago)
[–] Klear 2 points 5 months ago (1 children)

Pluto has more than one satellite?

[–] [email protected] 3 points 5 months ago (1 children)
[–] Klear 2 points 5 months ago

Must have missed that. Cool!

[–] [email protected] 6 points 5 months ago

I mean, we mostly only have info on our solar system for moon sizes. We could easily be an oddball, although it's not good science to assume we're special in any way.

[–] [email protected] 2 points 5 months ago* (last edited 5 months ago) (1 children)

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.

[–] [email protected] 2 points 5 months ago

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.

[–] [email protected] 2 points 5 months ago (2 children)

It wouldn't need to generate gravity.

Acceleration "down" would be enough.

[–] Scubus 7 points 5 months ago (1 children)

Only if it was undergoing constant acceleration, which we know it to be incapable of.

[–] [email protected] 2 points 5 months ago

It’s got sublight thrusters and steering doesn’t it? It could just fly around and around a circular path.

[–] [email protected] 3 points 5 months ago

I mean, those are equivalent forces. Gravity doesn't actually exist as a separate force, just like acceleration isn't a magical force appearing from nowhere.

[–] [email protected] 3 points 5 months ago

I ran the numbers, and it says about 0.00473m^2^2