[bobdihi (OP)]

What keeps our earth core from cooling down. And if it did cool down completely, would it effect our lives
Why is it hot in the first place?

[Ethos_]

As a result of the heavy bombardment, a great amount of heat energy has been stored up within the earth. Some have also speculated that the continuing output of heat energy may also be associated with some sort of nuclear reaction taking place within the core.

If the core ever looses enough heat for it to solidify, we would loose our protective magnetosphere. Loosing this protective magnetic envelope would indeed, result in great destructive changes for earths inhabitants.

[chris]

The Earth stays hot for three main reasons:

1) Radiogenic (radioactive) heat - as the isotopes inside the planet e.g. potassium-40 decay they produce heat.

2) Gravitational potential energy - some things are sinking towards the planet's surface because they are denser than the material around them; this is producing some frictional heating.

3) Embodied energy from formation - the process that forged the planet in the first place led to some heating. This includes being rammed by another near-Earth-sized planet about 4.5 billion years ago, which melted the entire Earth...