Exhibit Codex
The Moon
Earth’s natural satellite preserves an ancient record of impacts and volcanic activity.
Open interactive exhibit ↗About this exhibit
Natural satellite
Reference and coverage
Time scaling is shared with the interactive atlas. Surface interpretations and reconstructed history have different levels of certainty.
Planetary record
A record of impacts
Bright highlands are older than the broad dark basalt plains called maria. Without strong atmospheric erosion, many impact structures remain visible for billions of years.
Orbit & tides
The Moon keeps nearly the same face toward Earth because its rotation is synchronized with its orbit. Its gravity contributes to ocean tides. The atlas does not calculate lunar libration or eclipses.
Origins
A giant impact early in Earth’s history is the leading explanation for lunar formation. Details of the impact and subsequent evolution remain active research.
Time in this exhibit
4.6 billion years ago · Cloud & disk
The young Sun is surrounded by a disk of gas and dust. Planet formation is underway.
4.54 billion years ago · Young planets
The terrestrial planets are growing through accretion and impacts. Their orbits and surfaces continue to evolve.
Present · Modern system
Eight planets orbit our Sun. This layout compresses distances and adjusts sizes to make every world accessible.
Exhibit guide
Surface & geology
Impact craters, bright highlands and dark basalt plains preserve different parts of lunar history. Without liquid-water erosion or plate tectonics like Earth’s, many old features remain.
Bright highlands are older than the broad dark basalt plains called maria. Without strong atmospheric erosion, many impact structures remain visible for billions of years.
A giant impact early in Earth’s history is the leading explanation for lunar formation. Details of the impact and subsequent evolution remain active research.
Atmosphere & water
The Moon has an extremely tenuous exosphere. Ice can survive in permanently shadowed polar regions.
Orbit & rotation
The Moon rotates once per orbit, keeping approximately the same hemisphere toward Earth. A cycle of lunar phases takes about 29.5 days.
Earth–Moon system
The average Earth–Moon separation is about 384,400 km. Lunar gravity contributes to Earth’s tides. The Moon has no moons or rings of its own.
The Moon keeps nearly the same face toward Earth because its rotation is synchronized with its orbit. Its gravity contributes to ocean tides. The atlas does not calculate lunar libration or eclipses.
Exploration
Robotic missions and the Apollo landings supplied images, measurements and samples. Returned rocks help establish ages and test explanations of the Moon’s origin.
Read the detailed records
Open the full exhibit Codex for individual structure records and time-specific information. The Credits page lists source creators, licenses and adaptations.