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This silvery radioactive metal's name is derived from Pluto, which used to be regarded as the furthest planet from the Sun. In 2006, Pluto was downgraded from an official planet to a dwarf planet by the International Astronomical Union. Plutonium was the second transuranic element of the actinide series to be discovered. It has a half-life of millions of years
Trace amounts of plutonium occur naturally in uranium ores. Small quantities of this element have also been detected due to radiation leaks from nuclear facilities and the fallout of atomic bombs. However, plutonium is normally produced in nuclear reactors from uranium.
Plutonium is used mainly in the nuclear industry, including the production of nuclear weapons. Plutonium also provides essential fuel power in nuclear reactors and nuclear batteries. A piece of plutonium is warm to the touch because of the energy given off by alpha particle decay. American Apollo lunar missions used plutonium-233 to power seismic devices and equipment on the moon. Another significant isotope is plutonium-239, as a one kilogram mass can produce approximately 22 million kilowatt hours of heat energy.