Polonium is a chemical element with the symbol Po and atomic number 84. Polonium was discovered in July 1898 by Marie Curie and Pierre Curie and identified solely by its strong radioactivity. Polonium was named after Marie Curie's homeland of Poland. Polonium has few applications, and those are related to its radioactivity: heaters in space probes, antistatic devices, sources of neutrons and alpha particles, and poison. It is extremely dangerous to humans.