The length of lunar crater rays explained using secondary crater scaling

•Most ray lengths follow the trend: Radiuscrater1.27, except for the smallest craters, which have abnormally long rays.•Rays of larger craters are created when primary crater ejecta excavate bright, unweathered material from below the dark lunar soil.•Rays are primarily composed of locally derived material, but rays of small craters may be primary crater ejecta deposited on the surface.