Lat: 14.75°S, Long: 47.99°W, Length: 69.82 km, Depth: km, Rükl: 51
Left: LO-IV-149H In this Lunar Orbiter view, the smooth dark floor of 45-km Billy is partially visible in the upper left corner. The prominent 11-km circular crater to its southwest is Billy D. The definition of the IAU’s Rima Billy is not entirely clear, but it probably includes at least the feature at "B" (see Nomenclature).
Right: Two LROC views available from the global WAC series (Nearside, GL000).
Named from nearby crater. (Billy)
- IAU page: Rima Billy
- In the original IAU nomenclature of Blagg and Müller there were no rilles associated with Billy, but in the early 1960's, using Earth-based photos, the IAU-approved System of Lunar Craters added two. Using the traditional IAU system of designating rilles by Roman numerals, the rille at “A” in the Lunar Orbiter view shown above (seen then as extending all the way to the rim of Billy) was designated Billy Ir, while that at “B” (seen then as extending considerably beyond Billy D) was named Billy IIr, The rilles at “C” and “D” (possibly parts of the same feature) were not recognized. The intention of the modern name Rima Billy, and the date when it was approved, is not clear. The position and diameter given for it in the title line are taken from the on-line IAU Planetary Gazetteer. They tend to associate the current Rima Billy with the old Billy IIr of the System of Lunar Craters (the feature at “B” and extending to the north), but it is not known if that is correct or not. - JimMosher