Brian D. Fields

The helium in a party balloon is the very gas that makes it float. But long before balloons, helium appeared in the first minutes after the Big Bang. Its exact abundance in the universe is like a fingerprint: it tells you how many kinds of neutrinos (ghostly particles that pass through walls) exist.

Lunar soil is a garden that meteorite impacts constantly dig over. Instead of a shovel, asteroids shake up the surface, scattering cosmic dust and bringing deep layers to the top. This cosmic “tending of the bed” goes on for millions of years, creating a uniform layer.