From Wikipedia the free encyclopedia
For other uses see Geothermal .
Earth cutaway from core to exosphere.
In geology geothermal refers to heat sources within the planet. Strictly speaking geo-thermal necessarily refers to the Earth but the concept may be applied to other planets.
Geothermal is technically an adjective but in U.S. English the word has attained frequent use as a noun .
The planets internal heat was originally generated during its accretion due to gravitational binding energy and since then additional heat has continued to be generated by the radioactive decay of elements such as uranium thorium and potassium. The heat flow from the interior to the surface is only 1/20000 as great as the energy received from the Sun.
