Mare · Near side

Mare Imbrium

A vast basalt-filled impact basin dominating the northwestern near side.

Feature typeMare

RegionNear side

Approximate scale1145 km

LocationNorth-western near side

LRO Wide Angle Camera mosaic of the lunar near side showing Mare Imbrium as the large dark basin in the northwestern near side. Credit: NASA/GSFC/Arizona State University. View the NASA source and download information.

Mare ImbriumBasalt-filled giant impact basin · schematic locator aid

The schematic separates the landform concept from the spacecraft or telescope image above.

What you are looking at

Mare Imbrium occupies the floor of the enormous Imbrium impact basin. Dark basalt plains are ringed by mountain arcs and interrupted by craters, ridges and volcanic features.

How it formed and changed

The basin-forming impact excavated and restructured a huge region of the Moon. Later lava flows filled much of the basin interior, preserving a layered record of impact and volcanic history.

What scientists learn here

Imbrium ejecta affected a large fraction of the near side, which complicates attempts to interpret distant samples and crater ages. The basin is therefore central to debates about early lunar bombardment chronology.

How to find and observe Mare Imbrium

Mare Imbrium is easy to see with the unaided eye. Around first quarter, its mountain boundaries and crater rims cast strong shadows. Plato, Archimedes and the Apennine Mountains are excellent telescopic landmarks.

Nearby landmarks and exploration context

The Apennine Mountains form part of the basin rim to the south-east. Apollo 15 landed at the Hadley-Apennine boundary, while Copernicus lies south of the mare.

Why this feature matters

Its basin structure, lava plains and surrounding mountains preserve major episodes of lunar impact and volcanic history.

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