My university studies indicated a metallic core, basically nickel. I may be out of date though.

BWAHAHAHAHA! OK that's funny!

And not to mention, when you compress something, it heats. Which is why big turbo charged cars need intercoolers, compressing the air heats it, and it needs to be cooled post compression.

So basicly, if you an object smaller then the sun, but much larger thne Jupiter, you could get a surface tempurature liveable for humans, of course, the gravity would flatten you, but whatever. :)

I've got it!

A Kokeln Intercooler for the Earth's core!

Maybe a Cool Collar?

But since it's "Mother" Earth, isn't this disgusting to even think about, let alone discuss in public?

Ian