A transitional 'hollow" on the Moon, in morphology and size, between similar blow outs near the southwestern corner Mare Serenitatis. In appearance like a neolithic representation of a Whale, this feature is located on an otherwise nondescript area on the western floor of Mare Tranquillitatis (8.89147°N, 21.48729°E), near the February 1964 impact of the Ranger 6 spacecraft. LROC Narrow Angle Camera (NAC) observation M177494593R, orbit 11293, December 2, 2011; incidence angle 62.5° and at a resolution of 0.46 meters per pixel from 38 kilometers [NASA/GSFC/Arizona State University].
Joel RaupeLunar Pioneer
Hollows, as distinct from pit craters, have been discovered during the course of the Messenger survey of Mercury. As such, these new discoveries heightened awareness of similar features on the Moon, some of these well-known and others also newly discovered by LRO science teams.
Two hollows, or hollow clusters, for example, have been confirmed in LROC high-resolution images not far from the Moon's most famous example, "Ina," the "D Caldera" well-known to telescope observers looking for the challenging feature from Earth.
"Ina," (18.65°N, 5.3°E) an extremely young and unusual 3 by 2 km depression that may represent a gas eruption site on the Moon. LROC Narrow Angle Camera (NAC) observation ...