“Fat Man,” the atomic bomb dropped by the U.S. on Nagasaki, Japan, in 1945, carried about 6.2 kilograms of enriched plutonium, roughly the size of a softball. The origin of that deadly hunk of metal ...

For historical reasons, plutonium brings to mind nuclear weapons. Jan Hartmann brings another side of element 94 to attention, which features an upcoming trip to its eponymous celestial body.