The Moon keeps one face turned toward us not by coincidence but because it is tidally locked: its rotation period exactly matches its orbital period of 27.32 days. It spins once for every lap it makes around Earth, so the same hemisphere always faces home. This synchrony was built by gravity over billions of years. Earth raises a tidal bulge in the Moon’s solid body. When the Moon once spun faster, that bulge was dragged slightly ahead of the Earth-Moon line, and Earth’s pull on the offset mass applied a braking torque. Rotational energy bled away as internal friction until spin and orbit fell into lockstep. The bulge is now frozen in place, pointing permanently at us. A persistent myth: there is no “dark side”. Both hemispheres receive equal sunlight across a lunar month. There is only a near side and a far side. And we see more than half. Through libration we glimpse roughly 59% of the surface: - Libration in longitude: the orbit is elliptical, so orbital speed varies (Kepler’s s...