I know that Jupiter is called a “gas giant” – a planet made of gas, with a surface of clouded striations and a big red spot. But it has a huge mass, and a massive gravitational pull (I know – they’re the same thing). Can it really be gas all the way through? Wouldn’t it at least be crushed to liquid, of not to solid, by the time you get all the way to the center?
Caramel.
How it got there is a mystery.
Actually, it’s a really big diamond. Didn’t you read Arthur Clarke’s Oddysey series? 
Seriously, however, I don’t know. Sounds like a case for the Bad Astronomer.
Zev Steinhardt
My astronomy knowledge is probably out of date, but I do recall reading that it’s believed the center is metallic hydrogen.
http://galileo.jpl.nasa.gov/jupiter/core.html
Jupiter is a giant slushie with atmosphere!
What’s a little frightening about that analysis, Epimetheus, is when you realize that the slushie at the center is probably many times the radius of Earth.
Now that’s a big twinkie. Er, I mean slushie.
As Epimetheus says, nobody knows for sure. The pressures and temperatures are so high at the center of Jupiter, (or even, heck, if you just go a good fraction of the way down) that you can’t really do laboratory experiments to figure out how materials will behave.
The heaviest compoents, rock and metal, will sink to the core. (Again, as Epi sez, there’s a metallic hydrogen layer outside the core.) It’s hard to say whether silicates or metals would be solid or liquid at under those conditions.
Jupiter - the cosmic pastry.
Think that would would fly for a 23rd-century tourist advert?
Sombody (Sagan?) speculated that if Jupiter had been just a little more massive, it would have started to undergo thermonuclear chain reaction a long time ago and we’d be living in a binary system.
Like Tatooine. w00t. Think there’d be Jawas here?
according to the Nine Planets site the rocky core of Jupiter is
which at those pressures wouldn’t be all that much bigger than Earth. Re-reading your quote, you’re probably pretty close: several times the radius of Earth wouldn’t be that far off. (After going to all the trouble of looking the cite up, I wasn’t going to delete it just because I realized on preview that you were closer than I’d originally thought :)).
The same page I linked to above says:
How does one get metallic hydrogen? My chemistry is pretty good, but it’s not that good.
First get yourself a gas gun and read this article.
I guess I could just answer and say that it seems if you want metallic hydrogen you merely need to cool hydriogen to near absolute zero and then apply pressure equal to 1.4 million times that of earth’s pressure at sea level* and you’ll have it (although the linked article alos mentions a 3,000 Kelvin number…I think they are saying the sample heats up to that when the massive pressure is applied but I’m not sure.
[sub]* – Atmosphereic pressure on earth at sea level is defined as 14.7 pounds per square inch (it can vary but that’s the number i was given in my scuba lessons). So, you need a pressure of roughly 20.5 million pounds per square inch to get your metallic hydrogen.