 Lunar Orbiter 4 image | |
| Coordinates | 0°00′N4°54′E / 0.0°N 4.9°E |
|---|---|
| Diameter | 43 × 49 km |
| Depth | 1.6 km |
| Colongitude | 254° at sunrise |
| Eponym | Georg Joachim Rheticus |
Rhaeticus is a lunar impact crater that lies astride the equator of the Moon, on the southeast edge of the Sinus Medii. To the north-northwest is the crater Triesnecker, and due south can be found the worn remnant of the walled plain Hipparchus. The crater was named after Austrian astronomer Georg Joachim Rheticus. [1] [2]
The outer wall of Rhaeticus is heavily disintegrated, with rifts and notches in the northeast. The wall is most intact along the eastern face, while in the northwest it is little more than a low rise in the surface. There is also a low cut in the south-southeast wall. The overall shape of the rim is that of a rough hexagon that is slightly elongated in the north–south direction. The interior has been resurfaced by lava, and only a few low rises remain in the surface. Beginning at the crest of the eastern wall is a chain of craterlets that continue to the east-northeast for about a crater diameter. [3]
Running southwest from Rhaeticus to the crater Réaumur is a long rille, which is difficult to make out near Rhaeticus because of the group of mountains at that crater's southwest. The crater itself is 43 kilometers wide at one diameter and 49 kilometers long at another. It is from the Pre-Imbrian period, which lasted from 4.55 to 3.85 billion years ago. [2]
By convention, these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Rhaeticus. [4]
| Rhaeticus | Latitude | Longitude | Diameter |
|---|---|---|---|
| A | 1.8° N | 5.2° E | 11 km |
| B | 1.7° N | 6.8° E | 6 km |
| D | 0.9° N | 6.2° E | 7 km |
| E | 0.1° S | 6.0° E | 5 km |
| F | 0.1° S | 6.5° E | 18 km |
| G | 1.0° N | 6.4° E | 6 km |
| H | 1.0° S | 5.4° E | 6 km |
| J | 0.7° S | 3.2° E | 4 km |
| L | 0.2° N | 3.6° E | 14 km |
| M | 1.0° N | 3.8° E | 7 km |
| N | 1.2° N | 4.2° E | 12 km |
Ptolemaeus is an ancient lunar impact crater close to the center of the near side, named for Claudius Ptolemy, the Greco-Roman writer, mathematician, astronomer, geographer and astrologer. It measures approximately 154 kilometers in diameter.
Fabricius is a lunar impact crater that is located within the northeast part of the walled plain Janssen. Attached to the north-northwest rim is the slightly larger crater Metius. Fabricius has multiple central peaks that rise to 0.8 km, with a rugged rise to the northwest running north–south. The rim is lumpy and somewhat distended, most noticeably to the southwest and south. It is 78 kilometers in diameter and 2,500 meters deep. It is from the Eratosthenian period, 3.2 to 1.1 billion years ago. It is named after David Fabricius, a 16th-century German astronomer.
Thebit is a lunar impact crater located on the southeast shore of Mare Nubium. To the north-northwest is the crater Arzachel, and Purbach lies to the south-southwest. To the southwest is the flooded remnants of Thebit P, which is actually larger in diameter than Thebit itself.
Dembowski is a lunar impact crater located to the southeast of the Sinus Medii. Its diameter is 26 km. It was named after Italian astronomer Ercole Dembowski. To the east are the craters Agrippa and Godin, to the southwest is Rhaeticus.
Alpetragius is a lunar impact crater located on the eastern edge of Mare Nubium, to the southwest of the much larger crater Alphonsus. In the southeast is the prominent crater Arzachel, and to the west lies the flooded Lassell. Alpetragius is a Latinization of the name of Nur ad-Din al-Bitruji, a Spanish-Arab astronomer.
Horrocks is a lunar impact crater located entirely within the eroded northeast rim of the much larger walled plain Hipparchus. Its diameter is 30 km. It was named after the 17th-century English astronomer Jeremiah Horrocks. To the south of Horrocks are the craters Halley and Hind, Rhaeticus is to the north, and Pickering to the northeast. Gyldén and Saunder lie to the west and east, respectively.
Hommel is a lunar impact crater located in the southeast section of the Moon, in a region that is deeply impacted with a multitude of impact craters. The most notable craters nearby are Pitiscus to the north; Rosenberger due east; and Nearch to the southeast. The prominent crater Vlacq is nearly attached to the northeast rim. Also nearby is Asclepi to the west. Hommel is about 120 kilometers in diameter and its walls reach heights of 2,800 meters. It is from the Pre-Nectarian period, 4.55 to 3.92 billion years ago.
Triesnecker is a prominent lunar impact crater that is located in the Sinus Medii, near the central part of the Moon's near side. Its diameter is 25 km. It was named after Austrian astronomer Franz de Paula Triesnecker. It is located to the north-northwest of the crater Rhaeticus, and to the east-southeast of the flooded Murchison.
Aliacensis is a lunar impact crater that is located in the rugged southern highlands of the Moon. The crater Werner is located just to its north-northwest, and a narrow, rugged valley lies between the two comparably sized formations. To the southwest is Walther, and Apianus is to the northeast. Aliacensis is named after the 14th century French geographer and theologian Pierre d'Ailly in 1935. It is from the Nectarian period, which lasted from 3.92 to 3.85 billion years ago.
Delambre is a lunar impact crater that lies to the southwest of Mare Tranquillitatis, in the central highland region. To the west is the crater pair of Theon Junior and Theon Senior, the latter being more distant and located to the northwest.
Apianus is a lunar impact crater that is located on the rugged south-central highlands of the Moon. It is named after 16th century German mathematician and astronomer Petrus Apianus. It is located to the northeast of the crater Aliacensis, and to the northwest of Poisson. The worn crater Krusenstern is attached to the west-northwestern rim.
Geber is a lunar impact crater that is located in the rugged south-central highlands of the Moon. It lies halfway between the crater Almanon to the north-northeast and the crater pair of Azophi and Abenezra to the south-southwest. Farther to the southeast is Sacrobosco. Geber is 45 kilometers in diameter and 3,510 meters deep.
Donati is a lunar impact crater that is located in the rugged south-central highlands of the Moon. It lies just to the northwest of the crater Faye, and the two outer rims are separated by a gap of less than 10 kilometers. To the north is the comparably sized Airy, and farther to the southeast is Playfair. Donati is 36 kilometers in diameter.
Fontenelle is a lunar impact crater that is located along the northern edge of Mare Frigoris, in the northern part of the Moon. To the northeast is the remnant of the crater Birmingham. Due to its location, this crater appears oval in shape when observed from the Earth because of foreshortening.
Curtius is a lunar impact crater that is located in the southern part of the Moon. From the Earth the crater appears foreshortened, making it more difficult to observe detail. Nevertheless, this is a large crater that can be readily found in even small telescopes. Curtius is located within one crater diameter of the still-larger Moretus to the southwest. To the northeast is the smaller Pentland. Curtius is 95 kilometers in diameter and 6.8 kilometers deep. It is from the Nectarian period, 3.92 to 3.85 billion years ago.
Dyson is a lunar impact crater, 63 kilometers in diameter, that lies on the far side of the Moon, past the northwest limb. It is located in the northern part of the surface, to the northwest of the crater Coulomb, and east of van't Hoff.
Nearch is a lunar impact crater that is located in the southeastern part of the Moon, to the southeast of the crater Hommel. North of Nearch is Vlacq, and to the northeast lies Rosenberger. The crater is 76 kilometers in diameter and 2.9 kilometers deep. It is from the Pre-Nectarian period, 4.55 to 3.92 billion years ago.
Wilkins is a lunar impact crater that lies in the rugged highlands in the southeastern part of the Moon's near side. It is located to the southwest of the crater Pons and the long Rupes Altai scarp. Just to the southeast lies the larger crater Zagut, and to the north-northwest is the still-larger Sacrobosco. Wilkins is 57 kilometers in diameter.
Santbech is a lunar impact crater that is located to the southeast of Mare Nectaris. It lies south-southwest of the prominent crater Colombo. About one crater diameter to the east-northeast is the smaller Monge. The terrain around the crater, although rugged in places, has been flooded by lava and so has a low albedo and a relatively flat surface. It was named after the 16th-century Dutch mathematician and astronomer Daniel Santbech Noviomagus. It is from the Pre-Imbrian period, 4.55 to 3.85 billion years ago.
Kinau is a small, eroded lunar impact crater that is located in the low southern latitudes of the Moon. It lies to the southeast of the crater Jacobi, and about equally far to the north-northwest of Pentland. It is 42 kilometers in diameter and two kilometers deep. It may be from the Pre-Nectarian period, 4.55 to 3.85 billion years ago.
