The Moon: Earth's Nearest Neighbor

Of all the objects in the night sky, none is more familiar than the Moon — the only other world close enough to see in real detail with nothing but the naked eye. This short book explores the Moon from four angles:

How the Moon Was Born — the giant-impact hypothesis, in which a Mars-sized protoplanet named Theia is believed to have collided with the young Earth, giving rise to the Moon from the resulting debris.

A World of Craters and Seas — the lunar highlands, the dark basaltic maria, and the billions of years of impact history preserved on the Moon's surface.

Phases, Tides & Eclipses — why the Moon's appearance changes across the month, how it drives Earth's tides, and how solar and lunar eclipses occur.

Humans on the Moon — from the Apollo missions of 1969–1972 to robotic exploration and NASA's ongoing Artemis program.

Nearly everything known about the Moon up close comes from the Apollo missions, decades of robotic orbiters, and 382 kilograms of lunar rock and soil brought back for study — making it the best-studied object in the sky besides Earth itself, and still, in quiet ways, one of the least fully understood.