Lunar Probe
Impact basin · Far side / south

South Pole-Aitken Basin

An immense ancient impact basin extending from the lunar south polar region across much of the far side.

Feature typeImpact basin
RegionFar side / south
Approximate scale2500 km
LocationFar-side southern hemisphere
Orthographic lunar topographic view centred on the South Pole-Aitken Basin
Orthographic lunar topographic view centred on the South Pole-Aitken Basin. Credit: NASA/GSFC/Arizona State University. View the NASA source and download information.
South Pole-Aitken BasinAncient giant impact basin · schematic locator aid
The schematic separates the landform concept from the spacecraft or telescope image above.

What you are looking at

The South Pole-Aitken Basin is roughly 2,500 km across and is one of the largest and oldest recognised impact structures in the Solar System. Much of it lies on the lunar far side, so its scale is not obvious in ordinary Earth-based views.

How it formed and changed

The impact excavated deeply into the lunar crust and may have exposed material from lower crustal or mantle-related levels. Billions of years of later impacts and volcanism have modified the original basin morphology.

What scientists learn here

Topography, gravity, spectroscopy and samples from material influenced by the basin can test models of lunar differentiation and early bombardment. Chang'e 4's Von Kármán landing site lies within the basin, adding local surface measurements to orbital datasets.

How to find and observe South Pole-Aitken Basin

The basin cannot be viewed as a complete structure from Earth because it is predominantly on the far side. Global spacecraft maps are essential for understanding its full extent.

Nearby landmarks and exploration context

Von Kármán crater and the Chang'e 4 landing region lie within the basin. The lunar south-polar region overlaps its southern extent but should not be treated as synonymous with the entire basin.

Why this feature matters

Its size and depth make it a major target for studies of lunar crust, mantle materials and early Solar System bombardment.

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