30: Stardust, or Cosmic Poo?

Happy International Year of the Periodic Table, everyone! We’re celebrating 150 years since Mendeleev brought some order to the unruly mess of the elements of matter, organising all of the types of atoms into a system sorted by physics and chemistry: rows of increasing number of protons in the nucleus; columns of similar chemical properties due to the orbiting electrons. This week, Emily takes us through the Astronomer’s version of the table, which really only has three bits to it: Hydrogen, which is almost everything; Helium, which is almost everything else; and the rest, which is just called “metals”.