Polonium is a rare, highly radioactive metal that can glow with a faint blue light when it releases a lot of energy as it decays. A piece of polonium can get warm from its own radioactivity, which makes it both fascinating and extremely dangerous.

Marie Curie discovered polonium in 1898 while studying uranium ore in her Paris laboratory. The discovery of polonium helped scientists understand radioactivity and contributed to the work that earned Curie the Nobel Prize. She and her husband Pierre isolated polonium by processing tons and tons of ore to extract just tiny amounts of this mysterious element.

Polonium decays quickly, meaning its atoms break apart and release radiation at a fast rate. This makes it useful in certain scientific instruments and space equipment, where its heat can provide power. However, the same properties that make it useful also make it incredibly toxic. Even a speck smaller than a grain of sand can contain enough radiation to cause serious harm.

Because of its extreme radioactivity and rarity, polonium mainly appears in specialized scientific and industrial applications. Most people will never encounter it outside of chemistry textbooks, where it sits at atomic number 84 on the periodic table.