Plutonium Was Named After a Planet Named After a God of Death

The tradition of naming newly discovered elements after celestial bodies provided a fateful name for element 94. Following the discovery of uranium, named for Uranus, and neptunium, named for Neptune, the scientific community looked to the next planet in the solar system. In 1941, this was Pluto, a distant and dark world named by an eleven-year-old girl after the Roman god of the underworld. The discovery of element 94 was initially kept under wraps due to the ongoing secrecy of wartime research during World War II.

The team of scientists, led by Glenn Seaborg, had synthesized the new element at the University of California, Berkeley, in late 1940. Further research revealed that one of its isotopes, plutonium-239, was fissile, meaning its atoms could be split to release enormous amounts of energy in a self-sustaining chain reaction. This property made it a prime candidate for a new and powerful type of weapon. The name "plutonium" was formally proposed in March 1942, as its potential for destruction was becoming clear.

This connection to the god of death became tragically fitting. The immense power of plutonium was harnessed by the Manhattan Project, the top-secret American effort to develop nuclear weapons (Review). A plutonium core was used in the first-ever atomic detonation, the Trinity test, and in the "Fat Man" bomb dropped on Nagasaki in August 1945. Thus, an element named for a gloomy, distant world and its mythological ruler of the dead became inextricably linked to mass destruction on Earth.