RAY_REACH

How far a ray system reaches, in crater radii.

Tycho is 86 km across on a 1,737 km Moon and its rays run about 1,500 km, which is 35 of its own radii — the extreme rather than the norm, and it is the one every eye has seen. Sixteen is the working figure: Copernicus's system reaches roughly that, and a reach measured in radii means the same number serves a 90 km crater on Luna and a 900 km one on Iapetus.

universe/src/craters.ts:712