- Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon, and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous.
- Star Tales - Centaurus (ianridpath.com)
Centaurs were mythical beasts, half-man, half-horse. They were a wild and ill-behaved race, particularly when the wine bottle was opened. But one centaur, Chiron, stood out from the rest as being wise and scholarly, and he is the one who is represented by the constellation Centaurus (Κένταυσος in Greek).