| Coordinates: | -37.02°N 26.43°W |
| Diameter: | 71.79 km |
| Depth: | 1.8 km |
| Colong: | 335 |
| Eponym: | Augustinus Riccius and Matteo Ricci |
Riccius is a lunar impact crater that is located in the rugged, southeastern part of the Moon's near side. It was named after Italian astronomers Augustinus Riccius and Matteo Ricci.[1] It lies within one crater diameter southeast of the crater Rabbi Levi. To the east-northeast is Stiborius and due south is Nicolai.
This formation has been so heavily bombarded by subsequent impacts that it is nearly unrecognizable as a crater. Only the western and southwestern parts of the rim remains intact, the remainder having been obliterated by small craters. These craters also occupy parts of the northern and southern floor. Only a section in the northeast and near the intact western rim remain unmarked. This is perhaps the most defaced crater formation on the Moon that possesses an eponym.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Riccius.
| Riccius | Latitude | Longitude | Diameter | |
|---|---|---|---|---|
| A | 35.9° S | 27.4° E | 24 km | |
| B | 37.5° S | 27.8° E | 19 km | |
| C | 36.2° S | 28.8° E | 24 km | |
| D | 40.3° S | 28.9° E | 17 km | |
| E | 39.9° S | 26.4° E | 22 km | |
| G | 38.5° S | 24.4° E | 13 km | |
| H | 35.4° S | 26.1° E | 20 km | |
| J | 40.7° S | 26.0° E | 13 km | |
| K | 39.1° S | 25.7° E | 6 km | |
| L | 41.5° S | 26.8° E | 8 km | |
| M | 37.8° S | 26.4° E | 14 km | |
| N | 41.1° S | 27.6° E | 13 km | |
| O | 36.2° S | 27.8° E | 9 km | |
| P | 35.7° S | 28.1° E | 11 km | |
| R | 41.4° S | 30.7° E | 7 km | |
| S | 37.0° S | 26.5° E | 11 km | |
| T | 36.3° S | 25.0° E | 7 km | |
| W | 38.9° S | 25.2° E | 19 km | |
| X | 38.8° S | 26.7° E | 11 km | |
| Y | 35.8° S | 29.1° E | 10 km |