Why Everything Spins: From Ice Skaters to Planets

Long before Earth existed, a vast cloud of dust and gas began to collapse under its own gravity, and in that collapse, something ancient and elegant was born: spin. The conservation of angular momentum — the same principle that quickens an ice skater's rotation when she draws in her arms — set our planets turning 4.6 billion years ago, and they have not stopped since. From cyclones to solar systems, from draining water to orbiting worlds, rotation is not a curiosity of the universe but one of its deepest signatures. To understand why things spin is to understand something essential about how m