Riccius is a large, ancient lunar impact crater located in the southern hemisphere of the Moon.
Definition Riccius is a lunar impact crater, characterized by its heavily degraded state and complex interior, located in the Moon's rugged southern highlands.
Overview Situated in the south-central region of the Moon, Riccius has approximate coordinates of 37.1° S latitude and 46.5° E longitude. It is a large, worn formation, appearing as an irregular depression rather than a well-defined crater. Its extensive degradation is a result of prolonged bombardment by smaller meteoroids and seismic activity over billions of years. Due to its location, it is observable from Earth near the lunar limb during favorable librations.
Etymology/Origin The crater is named after Matteo Ricci (1552–1610), an Italian Jesuit priest and missionary. Ricci was a pivotal figure in the early modern cultural exchange between China and the West, known for his work in cartography, astronomy, and his efforts to introduce Western science and Christianity to China during the Ming Dynasty. The name was officially adopted by the International Astronomical Union (IAU) in 1935.
Characteristics
- Diameter: Riccius has an approximate diameter of 121 kilometers.
- Depth: Its estimated depth is around 2.8 kilometers from its rim to the floor.
- Rim: The rim of Riccius is extremely eroded, irregular, and heavily degraded. It no longer forms a continuous, distinct crater wall but rather appears as a low, broken ring of peaks and ridges. This ancient rim is interrupted and overlapped by numerous smaller, subsequent impact craters, particularly along its perimeter.
- Interior Floor: The interior floor of Riccius is uneven and heavily scarred by a multitude of smaller impact craters (craterlets) of varying sizes. While some sections may appear relatively flat, the overall terrain is complex and rugged. There is no significant central peak; instead, a prominent crater designated Riccius A lies near the center of the main floor. Other named satellite craters, such as Riccius B (overlapping the western rim), Riccius C (on the southeastern rim), and Riccius D (on the northeastern rim), further contribute to the formation's complex morphology.
Related Topics
- Lunar Nomenclature: The standardized system for naming features on the Moon's surface, managed by the IAU.
- Impact Cratering: The fundamental geological process responsible for the formation of most features on the lunar surface, often leading to subsequent degradation over time.
- Matteo Ricci: His historical contributions to cartography, astronomy, and cultural exchange between Europe and China, which led to his posthumous recognition in lunar nomenclature.
- Nearby Craters: Riccius is situated in a densely cratered region, with prominent neighboring formations including Rabbi Levi to the north, Nicolai to the west, and Borda to the south.