Astrophysics for People in a Hurry

The Periodic Table of the elements is one of humanity’s great achievements. A worldwide scientific effort, it organizes our understanding of the basic materials of our planet and how they combine to make the things around us, though it has needed contributions from astrophysicists to be fully understandable.

The Table is full of wonders. Hydrogen and oxygen, for example, behave in surprising ways: “One is an explosive gas, and the other promotes violent combustion, yet the two combined make liquid water, which puts out fires” (117). Ninety percent of the universe is made of hydrogen, the first and most basic element; two-thirds of the human body is hydrogen.

In the 15-million-degree heat at the center of the Sun, hydrogen atoms are fused into larger helium atoms and transform 4.5 billion tons of matter into energy every second in the process. Roughly 10% of the atoms in the universe are helium; all the rest of the elements make up a small fraction of 1% of the total.

The third element is lithium, an atom with three protons. Only 1% of all atoms are lithium, and all of it was created during the Big Bang; instead of being created inside stars, like helium, it gets destroyed there.