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Mr. X
2001-Oct-25, 03:42 AM
Does Jupiter have a "surface" per se? I mean if I had an indestructible space ship that also shielded me from heat, gravity, pressure radiation and other hazards, could I ever LAND it on something solid? Or if I accelerated like a maniac with my nose pointing at the center of Jupiter would I go through all the way to the other side? Same question about Saturn, Uranus and Neptune.

Someone said to me that it had no surface, just that the center was plasma. Is that right? And if I were at the center of Jupiter and looked outside my ship (indestructible, remember) what would I see? If I was in the upper atmosphere what would I see? Needless to say same question for Saturn, Uranus and Neptune.

I hope someone can make this clear for me once and for all!

GrapesOfWrath
2001-Oct-25, 03:57 AM
The density of Saturn is less than that of water, right?

But remember what happened to the comet Shoemaker-Levy, when it hit Jupiter. It produced some tremendous explosions, and left large marks on the planet. Kanamori had done some calculations and had predicted that the effects might even be visible at the antipodes.

David Simmons
2001-Oct-25, 04:47 AM
Try this site. Jupiter (http://www.geocities.com/athens/thebes/7870/composition.htm)

I would assume there are equivalent sites for the other gas planets. I found this through Yahoo! search.

MongotheGreat
2001-Oct-25, 05:29 AM
According to my understanding, all of the gas Giants have a solid core of heavy metals such as iron as well as metallic hydrogen. This takes extremely high pressure. Anyway, about SL-9 hitting Jupiter, it exploded not because it hit something solid, but because it hit something gaseous. Jupiter's atmosphere was thick enough to cause the comet to heat up extremely fast, causing the explosion.

GrapesOfWrath
2001-Oct-25, 11:25 AM
David's link says that Jupiter has a molten rock core that is fifteen times the size of the mass of the earth. And that the composition of Jupiter is similar to that of the Sun. So, does the Sun also have a molten rock core?

Mr. X
2001-Oct-25, 01:55 PM
Thanks.

So that would be gas, supercritical fluid, plasma, molten rock core.

If I had, again, a giant space vacuum cleaner, I put the end of the vacuum cleaner in jupiter and I turned it on. After a while, what would be left of Jupiter?

I mean it would suck in the gas, then the supercritical fluid would not be a supercritical fluid anymore because it would not be compressed by the upper atmosphere layers anymore but nevertheless I suck it in. Then I would have the previous plasma part, I would guess would no longer be plasma but I still suck it in. Then molten rock. I leave the molten rock there go back home, come back a couple million years later. Do I have a solid planet left, yes or no?

amstrad
2001-Oct-25, 02:14 PM
The Nine Planets (http://www.seds.org/nineplanets/nineplanets/nineplanets.html) is always a good reference for planetary data

Edit: my first post to the new board and i screw up the HTML /phpBB/images/smiles/icon_frown.gif

<font size=-1>[ This Message was edited by: amstrad on 2001-10-25 10:15 ]</font>

Mr. X
2001-Oct-25, 02:21 PM
Well, seems to corroborate what we had seen from that other place:



The gas planets do not have solid surfaces, their gaseous material simply gets denser with depth (the radii and diameters quoted for the planets are for levels corresponding to a pressure of 1 atmosphere). What we see when looking at these planets is the tops of clouds high in their atmospheres (slightly above the 1 atmosphere level).

Jupiter probably has a core of rocky material amounting to something like 10 to 15 Earth-masses.


So eventually I guess I would land on something more or less solid. But only after going through gas, supercritical fluid and plasma. Ouch.

Mnemonia
2001-Oct-25, 06:42 PM
On 2001-10-24 23:42, Mr. X wrote:
Does Jupiter have a "surface" per se? I mean if I had an indestructible space ship that also shielded me from heat, gravity, pressure radiation and other hazards, could I ever LAND it on something solid?


I'm not sure you could even call that landing. You can land on the Earth or Mars or the Moon becuase there is a very dense crust/ocean compared to the atmosphere or space above it. The interior of a gas giant would be more homogenous, so "landing" in a gas giant would be more akin to parking a submarine at an arbitary depth than landing an airplane on the ground. I think landing really has more to do with difference in surface pressure than contact.

<font size=-1>[ This Message was edited by: Mnemonia on 2001-10-25 14:43 ]</font>

Azpod
2001-Oct-25, 07:06 PM
First off, the Sun is a gas all the way through. The gas is heated both by compression and fusion energy to temperatures that prevent it from becoming a liquid, regardless of the immense pressure it is under. This is also regardless of what materials make up the gas. Iron, lead, carbon-- it doesn't matter; it's all superheated ionized gas.

The gas giants are another matter, however. While the core of a gas giant is heated by compression and also partially by radioactive decay of some rare isotopes, that doesn't give it enough energy to resist compression into a liquid indefinitely. I don't know if Jupiter's core is actually liquid, but it very well could be. I also don't know about Saturn, but Uranus and Neptune almost certainly have liquid, if not solid, cores.

As for the MegaMaid (TM) planetary vacuum cleaner, if you sucked out all of the light gasses (hydrogen, helium), you would be left with a mega-terrestrial planet with a mass about 15 times that of the Earth. It's likely that the gas giants started as terrestrial planets, howbeit big ones. When the Sun ignited and the solar wind blew the solar nebula away from the inner solar system, the planets of the outer solar system mopped up a great deal of the remaining gasses, becoming immensely huge in the process.

Interestingly enough, solar models for solar system formation predicts that gas giants are commonplace, and that they are often ejected from the young solar system by sibling rivals, often resulting in highly elliptical orbits that would eject (or consume) any terrestrial planets in the inner solar system.

If this is true, we can count ourselves lucky that our world isn't adrift between the stars. /phpBB/images/smiles/icon_biggrin.gif

Kaptain K
2001-Oct-26, 10:27 AM
Just because a planet has a gaseous atmosphere and a solid core, it does not mean that it has to have a surface. As the pressure gets higher, the density rises until it is indistinguishable from a liquid and from a liquid to a solid without a distinct phase change at any definable point. "Surface" implies a discontinuous phase change (on Earth: air to water or rock or water to rock).

_________________
All else (is never) being equal.

<font size=-1>[ This Message was edited by: Kaptain K on 2001-10-26 06:28 ]</font>

Mr. X
2001-Oct-26, 11:57 AM
On 2001-10-26 06:27, Kaptain K wrote:
Just because a planet has a gaseous atmosphere and a solid core, it does not mean that it has to have a surface. As the pressure gets higher, the density rises until it is indistinguishable from a liquid and from a liquid to a solid without a distinct phase change at any definable point. "Surface" implies a discontinuous phase change (on Earth: air to water or rock or water to rock).


Well that's what I was thinking, I couldn't really land with the little feet under my ship, but I could leave it "floating" on top of the new phase if it could ever float.

And I was thinking that with the vacuum cleaner (see earlier) it would leave me just after I am done with a ball of molten rock, not a real rocky place as in Mars or Mercury. Maybe if I waited a long time it would eventually be rocky? I don't really know.

beskeptical
2002-May-08, 07:25 PM
I wanted to see if adding something new brought this last page post to the front of the line so I wouldn't have to check pages of topics to find the ones that were current.

Sorry if I made anyone waste looking.

I would say, because I'm known to have an opinion on everything, isn't a gaseous state a function of temperature and pressure? If one calculates core temperature and core pressure wouldn't the question of a solid or liquid core just be a math problem?

Don't answer that. I'm sure no one wants to drag this old conversation out again. /phpBB/images/smiles/icon_smile.gif