Curium is a man-made element that belongs to the actinide series of elements. It was first produced in a laboratory in 1944 by bombarding plutonium with alpha particles. Curium is a highly radioactive metal that is silver in appearance and is chemically similar to the rare earth elements. It has some interesting and useful properties because it is so radioactive. By studying how curium behaves, scientists can learn more about how other elements behave in extreme conditions like those found in nuclear reactors or during nuclear explosions. Curium-242 is used in specialized batteries that power many types of space probes.