Lat: 25.5°S, Long: 29.2°W, Length: 191 km, Depth: km, Rükl: 53
LO-IV-132H Hippalus is the low crescent of flooded crater rim to the left of center in this view which extends to König on the right and to Campanus / Mercator at the bottom. The Roman numerals are the Hippalus rille numbers recognized by the IAU in the System of Lunar Craters and LAC maps. Rima Hippalus IV is very difficult to see with this lighting. For an Earth-based view at almost the same sun angle, remapped to the same scale and orientation, but showing an area slightly more to the right, see the image by Paolo Lazzarotti.
This family of three prominent rilles is concentric to the Humorum Basin and formed by bending of the crust as the center of the basin subsided due to the weight of the Humorum lavas.
- Note the Two Arcs (or Eastern and Western Arcs) of, what seems to be (or seems to have been) a complete crater, between Hippalus and Campanus (at the southern part of Rimae Hippalus).
- This formation (the Two Arcs) is easily detectable on Chart 23 in the 21st Century Atlas of the Moon (Wood/ Collins); just to the right (east) of the name Hippalus Rilles (location F6). Also on Chart 80 in the Times Atlas of the Moon, Chart 53 in Antonin Rukl's Atlas of the Moon, and Chart 94 (LAC 94) in the Clementine Atlas of the Moon. - DannyCaes Jan 6, 2014
- The LPI's Hi-Res scan of Lunar Orbiter 4's frame 132-h1 shows the Two Arcs near the frame's lower left corner (between Rimae Hippalus II and III, southwest of the bowl-shaped crater Campanus A).- DannyCaes Jan 6, 2014
- There's a similar formation on the eastern part of the floor of Eddington (the incomplete crater Eddington P). - DannyCaes Aug 5, 2014
- Named from nearby crater. (Hippalus)
- The original IAU nomenclature of Named Lunar Formations appears to have included the Roman-numbered Hippalus rilles I-III. Rima Hippalus IV seems to have been added in the System of Lunar Craters. The faint rille between the southern parts of Rima Hippalus I and II was designated Rima Hippalus V in NASA SP-241 (a non-IAU publication).
- In 1973 the IAU announced its intention of replacing the Roman numeral system for naming lunar rima with new names, but no action appears to have been taken on this.
- Two Arcs (or Eastern and Western Arcs); nicknames for the incomplete crater between Hippalus and Campanus. - DannyCaes Aug 5, 2014
L54: Rilles concentric to Humorum basin.
Harold Hill. A Portfolio of Lunar Drawings, page 134.