Lunar Probe
Mare region · Western near side

Oceanus Procellarum

The Moon's largest named dark volcanic plain, spanning a huge portion of the western near side.

Feature typeMare region
RegionWestern near side
Approximate scale2500 km
LocationWestern near side
LRO Wide Angle Camera mosaic of the lunar near side showing the broad dark Oceanus Procellarum province across the western side
LRO Wide Angle Camera mosaic of the lunar near side showing the broad dark Oceanus Procellarum province across the western side. Credit: NASA/GSFC/Arizona State University. View the NASA source and download information.
Oceanus ProcellarumExtensive basaltic volcanic province · schematic locator aid
The schematic separates the landform concept from the spacecraft or telescope image above.

What you are looking at

Oceanus Procellarum is the Moon's largest named dark plain, extending across much of the western near side. Unlike many circular maria, it does not correspond neatly to one obvious impact basin.

How it formed and changed

The region contains lava flows spanning a wide range of ages, volcanic domes, rilles and geochemical anomalies. Its origin and relationship to large-scale crustal structures have been investigated using GRAIL gravity data and global compositional maps.

What scientists learn here

Samples returned by Chang'e 5 from northern Oceanus Procellarum dated comparatively young basalts, demonstrating that lunar volcanism persisted much later than the ages represented by most Apollo samples.

How to find and observe Oceanus Procellarum

Procellarum dominates the western half of the visible lunar disk. A telescope reveals strong contrasts between smooth mare, bright craters such as Aristarchus and Copernicus, and sinuous volcanic features.

Nearby landmarks and exploration context

The Aristarchus Plateau, Reiner Gamma, Marius Hills and several Apollo-era robotic landing regions lie within or along the province.

Why this feature matters

It contains diverse volcanic terrains and hosted multiple robotic and sample-return missions.

Check lunar phaseCompare dates and illumination before observing.Plan an observing sessionUse phase-based target suggestions and keep the terrain in context.