Ray system

In planetary geology, a ray system comprises radial streaks of fine ejecta thrown out during the formation of an impact crater, looking somewhat like many thin spokes coming from the hub of a wheel.

Rays appear at visible, and in some cases infrared wavelengths, when ejecta are made of material with different reflectivity (i.e., albedo) or thermal properties from the surface on which they are deposited.

On non-atmosphered bodies such as the Moon, space weathering from exposure to cosmic rays and micrometeorites causes a steady reduction of the differential between the ejecta's albedo and that of the underlying material.

Low portions of FeO result in brighter materials, so such a ray system can retain its lighter appearance for longer periods.

Among the lunar craters on the near side with pronounced ray systems are Aristarchus, Copernicus, Kepler, Proclus, Dionysius, Glushko, and Tycho.

Fresh impact crater on Mars showing a prominent ray system of ejecta . This 30 m (98 ft) diameter crater formed between July 2010 and May 2012 (19 November 2013; 3°42′N 53°24′E  /  3.7°N 53.4°E  / 3.7; 53.4 ). [ 1 ]
Gratteri crater, a rayed crater on Mars that was imaged by THEMIS at night. An individual THEMIS image, of which this mosaic is comprised, is ~32 km across.
The rays of Kuiper , one of the freshest craters on Mercury