Why is Earth's interior is way hotter than its surface if it is farther from the Sun?

Question

The interior is so hot that is even capable of melting metals... lava.

Answer 1

It's from radioctivity and friction. The gas giants also create more heat than they recieve from the sun. The sun is nowhere the near the only source of energy in the solar system.

Answer 2

The earth's interior can be divided into three layers of contrasting composition: crust, mantle, and core. The interior of the earth has been determined using the characteristics of seismic waves. Two distinct mechanical layers, lithosphere and asthenosphere, can be identified in the outer 300 km of the earth.
Processes that operate on the surface of the earth are driven by energy from the sun (radiation).
Processes that operate within the earth are driven by heat energy from the radioactive decay of elements in the earth’s interior.
A fraction of the sun’s energy reaches the earth as solar radiation – the process by which heat passes through a gas, liquid or vacuum. Most solar radiation reaching the earth is absorbed by the land or oceans.

It is nuclear fission (radioactive decay) within the Earth which produces heat, drives mantle convection (more on this in the next unit), drives plate tectonics, volcanism, mountain building and earthquakes
Radioactive decay of the unstable isotopes of the following three elements produce most of Earth's heat (atom/isotope refresher):
Thorium: Thorium has many isotopes (atoms with the same number of protons - namely 90 for thorium - but different numbers of neutrons. 232Th (said "thorium 232") has 90 protons (or else it wouldn't be thorium) and 142 neutrons, for a total "mass number" of 232 (90 + 142). It is the isotope of thorium that produces the most heat in the Earth. 232Th has a half-life (time for half the thorium to decay), or t1/2, of 1.4x1010 years (14 billion years).
Uranium: Uranium has 92 protons. Again, uranium has many different isotopes, but one that produces the most heat in the Earth is 238U, which has 146 neutrons and therefore a mass number of 238 (92 + 146). 238U has a half-life (t1/2) of 4.5x109 (4.5 billion years).
Potassium has 19 protons. The isotope of potassium which produces the most heat in the Earth is 40K, which has 21 neutrons, and a half-life (t1/2) of 1.3x109 years (1.3 billions years).
The total amount of energy generated by 232Th, 238U, and 40K, is 3.8x1013 Watts, or 38,000,000,000,000 Watts, or 38 trillion Watts!
Most of the energy by radioactive decay in the Earth escapes as heat and eventually radiates into outer space.
However, a tiny bit of this energy is released in earthquakes: less than 0.001%!

Answer 3

Two words: radioactive isotopes. Google the term and see what you get. It's all based on Einstein's famous theory E=Mc^2, which relates energy to mass and the velocity of light squared. That means that tremendous amounts of energy (which is felt to heat) is produced by destroying a small amount of mass.

Answer 4

It's because the earths crust is a shell which is cooled while the inner core is still hot and the atmosphere cannot cool the inner core after all.

Answer 5

Because the atmosphere cools the upper crust through "Convection".

For details on convection=>

http://en.wikipedia.org/wiki/Convection

Answer 6

the rock is still wet !