This question was inspired by the people who wanted to dig a tunnel through the Earth and wrote to ask about the gravitational effects close to the center. I never thought this was a good idea, the chances of unleashing a Japanese monster being too great. But rather than waste the myriad drawings, plans and imaginative ideas, I propose we ship it all off to Uranus or some other gas giant and begin a trip to the center.
What’s involved? Could we build anything remotely capable of withstanding the astronomical temperatures / pressures that exist on the way down? If we assume we can (hey - it is not like I’m suggesting FTL travel here) what would the trip be like on the way down? As one got close to the center, would the pressure begin to subside due to the comparatively large amount of mass (and the corresponding gravitational effects) on the other sides of you? Is there a solid core to any of the gas giants? What happens to all of the rocks that have dropped in over the eons? Do they vaporize on the way down, or is there a core of collected material? If there is a core, any idea as to how to estimate its size? Could you stand on it and not get crushed by the weight of the surrounding atmosphere? If not, would you exclaim “The atmosphere - AHHHH” in you best Discovery Channel voice? Thanks,
Rhythmdvl
PS
My apologies if this is a double post. I waited a while, checked the GQ board and didn’t see it here. When I first tried I got the following message: Fatal error: Failed opening required ‘global.php’ in /home/httpd/html/sdmb/newthread.php on line 3. I really wish I could trust the CGI on this one.
My understanding about Saturn, Uranus, and Neptune
is that the gravity isn’t much different from here on
Earth - 25% more, or something, but not a real problem,
because they’re not too dense (gravity is also dependent
on the distance from the center of mass, of course, so
the ‘surface’ gravity is far enough away from the center
that the extra mass’ effect is muted).
As you go down, like you say, the pull of the gravity
from the mass you’re getting closer to will make it
stronger, while as you leave more and more mass ‘behind’
you it will pull in the opposite direction.
I think that the latest thinking is that Uranus and
Neptune may have tiny solid centers. I may have read this
in Scientific American, one of my kids’ copyright 2000
astronomy books, or I may be making it up. Can’t
remember.
PS Remember - some of the Japanese movie monsters came
from space!
Here’s a nice little chart that shows some interesting specs on our planetary neighbors.
However, I would caution you to take the “surface gravity” figures with a grain of salt; the “surface” of the gas giants is probably the upper atmosphere. Farther inward, where density increases to the point where hydrogen is a liquid and the inverse-square law changes things up, I think that the 14-times-greater mass of Uranus might create a “shell” of high gravitation that would be much higher than that of earth.
Arthur C. Clarke (of course) was the first to popularize the idea that some gas giants (Jupiter in his case) may have a core layer of solid diamond. This past month, Discover magazine (I know, I know) mentioned that the friction from a “diamond rain” falling towards the center of Neptune may explain the fact that Neptune radiates more heat than it receives from the sun.
Anyway, a diamond layer would be pretty damned difficult to cut through, so you can always use that as an excuse to quit worrying about it.
Uranus & Neptune are believed to have rocky (terrestrial planet-like) centers. They just have HUGE atmospheres (thicker than the rocky part). Jupiter & Saturn do not have terrestrial-like centers, although they certainly have gobbled up lots of minerals in their time.
I’ll have to check around for info on the pressures inside the gas giants.
The pressure inside Jupiter is so great that it has a metallic-hydrogen core kinda thing goin’ on.