Transcript: The heaviest elements are fantastically rare compared to hydrogen and helium because they can only be produced in massive stars which are far less numerous than stars like the Sun. But what does it mean to say that gold is a trillion times less abundant than hydrogen? Imagine the analogy of a deck of cards. One in twelve atoms is a helium atom. So the deck would have its aces as helium atoms, and all the other cards would be hydrogen atoms. Oxygen has an abundance of one part in 1,500 relative to hydrogen, so that means we would have to search twenty-eight decks of cards before we found one oxygen atom. Gold is far less abundant; we would have to search ten billion decks of cards to find a single gold atom. It’s a testament to the incredible power of the technique of spectroscopy that astronomers can routinely detect elements that have a cosmic abundance of about one part in 1012.