[Mmogamer]

True I was just saying a rocky type like Earth probably couldn’t however.

[Oceander]

True I was just saying a rocky type like Earth probably couldn’t however.

Fair enough. On that point I think you're almost certainly correct; anything that was large enough, and radioactive enough, to keep itself heated wouldn't have a rocky surface; it might have some sort of a surface, but there would almost certainly have to be a lot more interchange between the atmosphere and the underlying, heated, materials than there is on a rocky body on a par with Earth.