What Causes the Moon's Craters

The Moon's surface is covered in craters almost entirely because of asteroid, comet, and meteorite impacts over billions of years, not volcanic activity — a scientific conclusion reached firmly by the time of the Apollo missions, when astronauts collected lunar rock samples geologists could analyze directly and confirm impact origins for the vast majority of the Moon's craters.

Craters form when a fast-moving object strikes the surface hard enough that the sudden release of kinetic energy behaves essentially like an explosion, excavating material outward and leaving a roughly circular depression (impacts almost always produce circular craters, even from an object hitting at a steep angle, because the physics of the resulting explosion radiates outward relatively evenly regardless of the impactor's original approach angle).

The Moon has vastly more visible craters than Earth for a specific, well-understood reason: Earth is struck by roughly similar numbers of objects over time, but Earth has active plate tectonics, erosion from wind and water, and vegetation that erase most impact evidence within a relatively short geological time — while the Moon has none of these processes (no atmosphere, no water, no active plate tectonics), so craters that formed billions of years ago remain almost perfectly preserved today.

The large, darker, relatively smooth areas visible on the Moon's near side — called maria (Latin for "seas," though they contain no water) — are ancient basaltic lava flows that filled in enormous, older impact basins roughly 3 to 3.5 billion years ago, before the Moon's interior cooled enough to stop volcanic activity. So while craters themselves are from impacts, the flatter maria regions between and around them are genuinely volcanic in origin, just from a much earlier era of lunar history.

The Moon's far side (never visible from Earth — see our dedicated guide on why) has dramatically fewer maria and a much more heavily cratered appearance than the near side, a genuine asymmetry scientists attribute to differences in crustal thickness between the two hemispheres, which affected how easily ancient lava could reach the surface on each side.

The largest confirmed impact basin on the Moon, the South Pole–Aitken basin on the far side, spans roughly 2,500 kilometers across and is one of the largest known impact structures in the entire solar system — a scale of ancient collision that dwarfs anything visible among the Moon's more commonly photographed near-side craters.

Crater counting is itself a genuine scientific dating technique: because craters accumulate at a roughly known rate over time, a more heavily cratered surface is generally older than a less cratered one, letting scientists estimate the relative age of different lunar regions (and, by extension, other planetary surfaces) without needing a physical sample from every location.

Even basic binoculars reveal genuine crater detail along the terminator, meaning you don't need a telescope to start observing the impact history this guide describes for yourself.

The Moon's relatively small size and lack of a substantial atmosphere also mean it cooled and solidified faster than Earth after formation, preserving a much older, less geologically modified surface record — one reason lunar samples have been so valuable for understanding the early solar system's impact history, since Earth's own ancient impact record has been mostly erased by plate tectonics and erosion.

Crater naming follows an official process managed by the International Astronomical Union, which assigns names (often after deceased scientists, explorers, and other notable historical figures) to maintain consistency across the global astronomical community rather than allowing informal or duplicate naming.

A basic geology textbook's chapter on impact cratering, even one focused on Earth, translates directly to understanding lunar craters, since the underlying physics of a high-speed impact is the same regardless of which body it strikes.

Some of the Moon's youngest, most visually striking craters (like Tycho, with its dramatic ray system) are estimated to be only around 100 million years old — genuinely recent by lunar-history standards, even though that's still far older than most geological features on Earth's own constantly-renewing surface.

A rewarding beginner project: sketch what you see through binoculars during a single session, then compare your sketch to a labeled Moon map afterward to check your own crater identification.

Comparing a young crater's sharp, well-defined rim to an older, more eroded-looking one is a genuinely satisfying way to spot relative age differences with nothing more than binoculars.

Watching the same crater's shadow shift across several different phases over time is a rewarding long-term observing project for anyone with nothing more than basic binoculars.

Shadow, not color, is what actually reveals a crater's true depth and shape.

Age leaves a visible mark on every surface.