Potassium-40 heats up Earth's core May 7, 2003 Radioactive
potassium could be a significant source of heat in the Earth's
core. V Rama Murthy from the University of Minnesota and
colleagues have shown that potassium-40 can exist in the core of
the Earth and provide heat via its radioactive decay. The result
could have important implications for theories of thermal
evolution of planetary cores and the origin of geomagnetic
fields (V Rama Murthy et al. 2003 Nature 423 163). Potassium-40,
which has a radioactive half-life of about 1.2 billion years,
could be an important source of heat in the Earth’s core but
this has never been unambiguously confirmed in an experiment.
Murthy and colleagues used an iron and iron- sulphur mixture to
represent the Earth's core and potassium silicate glass to
represent the shell. They measured the partition coefficient -
the concentration of potassium-40 in the sulphur mix divided by
its concentration in the silicate - at temperatures and
pressures approaching those found deep in