PAPER 8 OF THE LEF SERIES
The Crater-Poor Centre of South Pole–Aitken
A heat source beneath the far side, opposite the near-side openings, erased the craters of the basin's centre
Abstract
South Pole–Aitken (SPA), the largest and oldest basin on the Moon, should hold one of its fullest crater records, yet its centre is crater-poor. The count is made in rings from the middle of the basin, on ground cleaned of the lava plains and of the 34 maria of this series. It rises steadily from centre to rim, and the central region holds about half the craters found just outside the basin. The minimum lies about 270 km north-north-east of the centre, on the meridian of the antipode of Serenitatis. Craters of 20–40 km are the most depleted. Those that remain are shallower than those of the rim belt while their rims stand high: their floors crept back up over softened ground, the pattern of relaxation rather than erosion or burial. We propose that the centre of SPA records a heat source beneath the far side. It lay opposite the near-side openings through which the young Moon was fed while attached to the Earth, and had two exits, facing Imbrium and Serenitatis. The heat raised the region into a dome, drove off volatiles and compacted the returned layers. It concentrated the iron that remained into the dense mass beneath the south of the basin. As the heat calmed, before release, the dome cooled, contracted and collapsed into today's deep basin. The dome lies south of both exits, displaced by the connection to the Earth and by the Earth's rotation. The rounding of the body enlarged that offset from 17–21° to today's 24–29°.
Keywords: Moon; South Pole–Aitken basin; crater density; viscous relaxation; lunar far side; antipodes; lunar origin
How to cite
Duran, Z. (2026). The Crater-Poor Centre of South Pole–Aitken: A heat source beneath the far side, opposite the near-side openings, erased the craters of the basin's centre. Paper 8 of the LEF series. https://lef-model.com/paper08.html