Planet size and gravity

I was just thinking about all the planets and moons we've seen in the Star Wars films -- all the inhabited ones anyway. Since all species seem to have the same weight, and walk, run, jump and in every other way interact with the environment the same way as on our Earth, is it reasonable to assume all the worlds in the Saga are the same size as Earth, indicating a consistent gravitational pull throughout? Perhaps a Jedi Council topic at the official site has touched on this...

 

Coruscant, according to a few books, is supposed to have 1.5 times Earth's gravity. Each indivdual abode, whether speeder or home, has its own gravity control to make the occupants feel at home.

There is hardly any chance that any two world swill be the same gravity, although they can come close like Earth and Venus.

That 1.5 times Earth gravity might be 1.5 times Alderran or Naboo, I don't recall exactly.

 

Geonosis has slightly less gravity.
This is the bad exuse (but official) for why Padme didn't get seriously injured when she fell out of the ship.

 

Really, that's the 'official' reason given for Padme falling and not getting hurt on Geonosis? Ah, yes, let's call it the "suspend all disbelief" gravitation pull. ;-)

 

Padme didn't get seriously hurt cause her big old bum cushioned her fall.

 

Geo's low gravity also explained how R2 was able to fly in a planetary environ.

 

Not to mention those stupid rockets (that "disappear" in the OT)

 

Who says they disappeared?
Where would he need to use them?
R2 has a lot of one-shot wonders.
The fire extinguisher
The radar sensor
The spring launcher
The buzzsaw
And the Ewok Zapper
Just because he has something doesn't mean he has to use them all the time especially when unneccesary.
In other words, say you saw RotJ first. Would R2 having a radar disk seem ludicrous in ESB just because he doesn't use them in RotJ?
As a droid that works with starships, having rocket boosters only makes sense. How else would he access the harder to reach areas of a ship in the depths of space?
But this is off-topic.
If you'd like to continue discussing this, I spose someone could always start an R2's gadgets thread.

 

"And the Ewok Zapper"

Wasn't it also a Yoda zapper? I recall sparks when Yoda hit him.

My biggest gripe against the rockets is that it was simply added as a pretty visual to the droid factory, which itself was added as a pretty visual. Neither the rockets nor the factory were necessary for the plot, but that's just me.

 

No, it was only the Ewoks and Salcacious Crumb (sp?)(Jabba's pet monkey thing)

 

That's it! I knew there was someone else who was zapped.

BTW, getting back on topic, shouldn't the title of this thread technically read "Planet mass and gravity"?

"Size matters not" ....Gallileo.

 

There's lots of issues with gravity and planet mass.

If I think about it, I can't get my mind around a planet being 'hollow' and filled with water (Naboo) so that you can travel through the planet's core.

Since Naboo has a night and day, the planet is obviously spinning. The earth spins also and our planet's core is molten (rock/metal) and also thru some kind of momentum, keeps the planet going (I did very badly in Physics, so stop me any time) in a vacuum, but this spin also creates centripetal force which is related to gravity. So the closer you get to a spinning sphere's core, the stronger the force...I don't think it's possible...

Many issues.

 

"but this spin also creates centripetal force which is related to gravity. So the closer you get to a spinning sphere's core, the stronger the force...I don't think it's possible"

You mean centrifugal force, which is in the opposite direction (actually, it's at a right angle, in the direction of the spin) direction from gravity, so they can "counteract" each other. be grateful that the Earth's gravity is stonger than the centifugal force created by our spin.

As such, the water pressure created as you near the planet's core increases logarithmically (I recall that you get the pressure of 2 atmospheres at 30 feet of depth, but I'm not sure.)

As you reach the core, the centrifugal force lessens, since the rate of spin decreases (the outer rim of a wheel rotates faster than the inner rim.)

 

Trojan Sock

According to my Physics (college) book and being corrected by a person on this board who was working on her master's in mathematics (or so she said), there is no such force as centrifugal. Only centripetal (a center seeking) force.

There is a definition for centrifugal n my Websters Unabridged Dictionary, but not my Physics textbook (and it's not a cowboy Physics book either, it's the Physics text for science majors). ?

 

"there is no such force as centrifugal."

Well, there is some matter for debate, I can assure you. The other term that it is associated with is inertial force (this will be in your physics book). It is essentially the feeling of resistance against your seatbelt when you oversteer your car. Your body wants to continue in the same direction, and is prevented from doing so by another object. This falls in line with Newton's first law of motion - "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." (This is sometimes referred to as The Law of Inertia)

I prefer the term "centrifugal" because I've always associated that word with the effect (and most people tend to understand the word), but it is by no means the definitive word on the subject. I'm not going to go into full physics descriptions here, but I have some good links if you are really interested.

Very technical descriptions

Good pics

Fun with slinkies

Basically, I use the terms interchangeably, because I don't get into frames of reference (at least for this...I do use them to explain Einstein's time travel theorem and the "Twin paradox." )

 

Thanks, Trojan Sock!

Believe me, I'll stick with biology.

Your name sounds vaguely naughty for some reason...

 

It refers to the horse, not the prophylactic.

 

Found a little info. I browsed through the Role Playing Game for SW, there is a planetary guide for Coruscant saying that it is 12,640 km in diameter. The Earth is 12,700 km in diameter. Gravity would then be similar depending on Coruscant's density. Alderran and Naboo were slightly smaller as well.

 

"Gravity would then be similar depending on Coruscant's density."

Very true, but don't forget the planet's rotation as well. How long are the days, compare to Earth (not that we'll ever really know.)

Also, does Coruscant have any natural satellites? (moons)

 

I didn't read into the RPG supplement to deeply, but I do have "Inside the Worlds of Star Wars Episode I". It's sorta like an Incredible Cross Sections book.

It says that Coruscant system has 1 sun and 4 moons.

EDIT: I have not looked, but I think there is at least one shot of Coruscant's moons in the PT.

 

*quick jump in*
I knew used the zapper someplace else! But it slipped me mind

 

Planet Size and Gravity not having much bearing on many sci-fi novels or movies is one of the classic examples of fudging that goes on in sci-fi in order make it relatable to us mortals that can't go into space. It's just too impractical to do all that gravitational realism in a movie: it slows the story down, and such unearthly realities that most people don't even have a point of comparison on tend to be bad for drama. It's the same as the fact that all starships tend to travel in the same orientation and the same plane in Star Wars (and Star Trek, and just about any other SF film).

-JDR.

 

"It's the same as the fact that all starships tend to travel in the same orientation and the same plane in Star Wars (and Star Trek, and just about any other SF film)."

Not to bicker, but it's not unreasonable to assume that ships traveling together would maintain a similar attitude (pitch, yaw, roll) with each other, since years of planet-born existence would make random attitudes seem "unnatural" or uncomfortable (though perhaps people born in space would not suffer from this.)

When I played X-wing, my playing improved dramatically when I learned to control my roll, thus allowing me to get a better view of my targets (especially on the training course.)

Of course, there were many missions where the target ships themselves traveled in the same plane (which tended to make them easy pickin's ) but again, they were designed by earth-bound mortals.