Thread: lava planet

Something just popped into my head and I'm wondering if it's at all possible.

What if a planet is composed of some of the heavier elements and the planet is huge? Could the gravity cause such high pressure that it melts all the matter and creates just a huge ball of lava?
Would the cold space around the planet cause the surface to harden and become solid? Or is it possible that the planet would be SO huge that it wouldn't freeze?

I'm just wondering if there is a way to have a huge ball of 'fire' in space that isn't a star.

Pressure generally raises the melting point, rather than lowering it. The more relevant question is 'what is the temperatute of the planet'.
This will be contigent upon the following:
1) Incident radiation (primarily from the system's star)
2) Heat of formation - largely conversion of kinetic energy to thermal during impact.
3) Radioactive content.

The early Earth was molten and thus a huge ball of 'fire' in space that isn't a star for several millions of years at least.

aaah cool! So how bright would something like that be? Obviously much dimmer than a star, but how much dimmer?

Many orders of magnitude dimmer. Not only is the temperature lower, but the surface area is dramatically smaller.
If I have time I shall try to work out a comparison with a typical red dwarf.

thanks but you dont gotta. its not that important.

Question, that popped into my head; a black hole radiates heat, doeas this heat source radiation of the black hole radiate forever or is it limited?

Im reffering to the can never freeze part.

It radiates until the black hole runs out of mass. Ie. the radiation carries away it's mass, very slowly. Or so I understand.

As for the first question:

Usually, a planet that's massive enough retains more of the lighter elements. The main reason Mars or the Moon don't have atmospheres is because their gravity is too low to keep one around them. Jupiter and Saturn are almost all light elements because they're big enough to retain more.

Originally Posted by Ophiolite

PostPosted: Sat May 12, 2007 8:22 am Post subject:
Pressure generally raises the melting point, rather than lowering it. The more relevant question is 'what is the temperatute of the planet'.

It raises the melting point, but it also raises the temperature.

Originally Posted by kojax

It radiates until the black hole runs out of mass.

If the black whole is continuously sucking in matter, then it will not run out of mass. That is, unless the radiation manages to "erode" more mass than is sucked in...