what is lunar surface

The lunar surface is the outermost layer of the Moon, which has been shaped by large impact events and many small ones, forming a landscape featuring craters of all ages. The surface of the Moon is divided into two main regions: the heavily cratered highlands and the smooth dark lowland maria, which are most prominent on the near side. The prominent lunar maria were produced by volcanic activity. Blanketed on top of the Moons crust is a highly comminuted and impact-gardened mostly gray surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder. The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–15 m (33–49 ft) in the highlands and 4–5 m (13–16 ft) in the maria. The topography of the Moon has been measured with laser altimetry and stereo image analysis. Its most extensive topographic feature is the giant far-side South Pole–Aitken basin, some 2,240 km (1,390 mi) .