earth

It's a combination of radioactivity (the radioactive materials in the Earth generate heat) and the residual heat from the formation of the Earth. When all of the matter that created the Earth fell together, it picked up kinetic energy falling in. When it stopped at the proto-Earth, the kinetic energy was turned into heat. The Earth hasn't cooled yet. The Moon, being much smaller, has had time to cool and probably has a solid core.

Earth (IPA: /'??(r)?/, often referred to as the Earth, Terra, the World or Planet Earth) is the third planet away from the Sun, and is the fifth largest planet in the solar system. It is also the largest of its planetary system's terrestrial planets, making it the largest solid body in the solar system, and it is the only place in the universe known to humans to support life. It is also the densest planet in the solar system. The Earth was formed around 4.57 billion years ago[1] and its natural satellite, the Moon, was orbiting it shortly thereafter, around 4.53 billion years ago. The outer surface is divided into several tectonic plates that gradually migrate across the surface over geologic time spans. The interior of the planet remains active, with a thick layer of convecting yet solid mantle and an iron core that generates a magnetic field. Its atmospheric conditions have been significantly altered by the presence of life forms, which create an ecological balance that modifies the surface conditions. About 71% of the surface is covered in salt-water oceans, and the remainder consists of continents and islands

I don't really know but I think it is that way because there isn't alot growing in the middle of earth.

dont know if the center of the earth is hot..do you?? give me some information on it

I thought it was gravity pulling things so tight that it builds heat.