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Tuesday, July 19, 2011

Radioactive decay and the inner heat of Earth

Scientists now estimate that the Earth produces some 44 trillion watts (44 terawatts) of heat, but they can only account for about half of it. We all know that the Earth runs on massive amounts of heat - Where does this come from? One trillion is 1000 billion.
About half of the heat that the earth generates itself is due to radioactive decay, scientists have concluded. While a recent study published in Nature Geoscience by the Japan-based KamLAND collaboration (which runs an important radiation detector) has shed light on processes deep within the bowels of the planet, it still leaves open the question of what's generating the other half?

This new discovery shows that the planet still retains an extraordinary amount of heat it had from its primordial days.

Earth's internal radioactivity and its primordial heat will both diminish in future years, says David Stevenson, a planetary physicist at the California Institute of Technology in Pasadena. The planet is now cooling about 100°C every 1 billion years, so eventually, maybe several billions of years from now, the waning rays of a dying sun will shine down on a tectonically dead planet whose continents are frozen in place.

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