Arrow identifies the location of interesting wrinkled ridges within Aitken crater. The South Pole–Aitken basin (SPA Basin, / ˈ eɪ t k ɪ n /) is an immense impact crater on the far side of the Moon.At roughly 2,500 km (1,600 mi) in diameter and 13 km (8.1 mi) deep, it is one of the largest known impact craters in the Solar System.It is the largest, oldest, and deepest basin recognized on the Moon. The South Pole-Aitken basin is oval-shaped, as wide as 1,600 miles (2,500 km) and 8.1 miles (13 km) deep. Image credit: NASA/Goddard › Larger image This LOLA image centers on the South Pole-Aitken (SPA) basin, the largest impact basin on the Moon (diameter = 2600 km), and one of the largest impact basins in the Solar System. South Pole-Aitken (SPA) basin, the biggest and most ancient lunar basin. As SPA is the deepest impact basin on the Moon, more than 8 km (5 mi) deep, the deepest lunar crustal materials should be exposed here. The South Pole–Aitken basin is so named because it stretches between Aitken crater and the south pole. Mountains on its edge, remnants of outer rings, are red and yellow. In fact, the Moon's lower crust may be revealed in areas within SPA: something not found anywhere else on the Moon. A view of the Moon's largest impact feature, the South Pole–Aitken basin, based on images from NASA's Lunar Reconnaissance Orbiter. The Moon's Largest Impact Basin 07.14.10 A crater within a crater within a basin: the interior of the South Pole-Aitken basin is one of the most compelling destinations on the moon. Despite its size, it cannot be seen from Earth because it is on the far side of the Moon. Credit: NASA… The low center is dark blue and purple. The orthographic projection here centered on the basin (53°S, 191°E) highlights how much of the lunar farside was affected by this ancient impact … It's easily seen in the elevation data. The South Pole-Aitken Basin on the lunar far side is one of the largest and oldest impact features in the solar system. Image width is 250 km.