[aruanan]

Hmmm. I don't see how lack of heat produces water, methane and ammonia.

That wasn't claimed. But based on the fact that all the outer planets (except Pluto) are gas giants and many of them have moons that are covered with ice and methane slushes, it's not unreasonable to posit a planet that is even farther out than Pluto would be cold enough to be covered with ice, ammonia, and methane.

[Rudder]

I was joking a bit about the cold, but I did wonder where the chemicals came from, whether it was a gas or solid planet.