Coordinates | 6°48′N122°18′E / 6.8°N 122.3°E Coordinates: 6°48′N122°18′E / 6.8°N 122.3°E |
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Diameter | 89 km |
Colongitude | 239° at sunrise |
Eponym | Abbas Ibn Firnas |
Ibn Firnas is a lunar impact crater on the far side of the Moon. Attached to the exterior of its southwestern rim is the prominent crater King. Only a few kilometers to the north, separated by a rugged stretch of terrain, is the larger crater Ostwald.
Ibn Firnas is a worn and eroded crater with small impacts along the northern and eastern rims. The satellite crater Ibn Firnas L lies along the inner wall to the southeast and covers part of the interior floor. Along the northern side, the small satellite crater Ibn Firnas Y cuts through the rim and overlays part of the inner wall. The interior floor is irregular along the northern and southwest sections where their shape has been modified by the large nearby craters mentioned above. Several small craters lie across the remainder of the interior floor.
In 1976 the crater was named by the IAU after Abbas Ibn Firnas, a polymath from Andalucia who, [1] in the 9th century, devised a chain of rings that could be used to simulate the motions of the planets and stars. Prior to 1976, this crater was known as Crater 213. [2]
Several small craters located in the rugged terrain at the northern edge of this crater have been assigned names by the IAU. These are listed in the table below.
Crater | Coordinates | Diameter | Name source |
---|---|---|---|
Carol | 8°30′N122°18′E / 8.5°N 122.3°E | 8 km | Latin feminine name |
Ewen | 7°42′N121°24′E / 7.7°N 121.4°E | 3 km | Gaelic masculine name |
Kasper | 8°18′N122°06′E / 8.3°N 122.1°E | 12 km | Polish masculine name |
Melissa | 8°06′N121°48′E / 8.1°N 121.8°E | 18 km | Greek feminine name |
Romeo | 7°30′N122°36′E / 7.5°N 122.6°E | 8 km | Italian masculine name |
Shahinaz | 7°30′N122°24′E / 7.5°N 122.4°E | 15 km | Turkish feminine name |
The crater Melissa lies across the north-northwestern outer rim of Ibn Firnas. It is a roughly bowl-shaped, although it has a very uneven appearance due to the irregular terrain in which it was formed. Melissa was previously designated Ibn Firnas Y before it was assigned a name by the IAU.
The locations of these craters are shown on the following L&PI topographic maps:
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Ibn Firnas.
Ibn Firnas | Latitude | Longitude | Diameter |
---|---|---|---|
E | 7.5° N | 125.5° E | 42 km |
L | 5.9° N | 123.0° E | 21 km |
Zanstra is a lunar impact crater that is located on the far side of the Moon. It was named after the Dutch astronomer Herman Zanstra. It lies to the southeast of the crater pair Ibn Firnas and King, and northwest of Gregory. This is a low, eroded formation that is difficult to distinguish from its surroundings. The interior floor is level and not significantly impacted.
Zwicky is a lunar impact crater that is located on the far side of the Moon. It lies to the west of the crater Aitken, and is attached to the western rim of Vertregt. Attached to the northern end of Zwicky is Heaviside. Zwicky is a considerably eroded formation with an irregular rim and interior. Portions of the southern rim still survive, but the remainder has been almost completely eradicated.
Vitruvius is a small lunar impact crater that lies on the northern edge of the Mare Tranquillitatis. To the east is the crater Gardner, and to the northeast is Fabbroni. To the north-northwest is the elongated Mons Vitruvius mountain, and beyond is the valley where the Apollo 17 mission landed.
Alfraganus is a small lunar impact crater that lies in the rugged highland region to the southwest of the Mare Tranquillitatis. It is named after the Arab Muslim astronomer Alfraganus. Northwest of Alfraganus is the crater Delambre, and to the south is the irregular Zöllner. The rim of Alfraganus is circular and retains a sharp edge that has not received a significant amount of wear due to subsequent impacts. The interior floor is roughly half the diameter of the crater rim.
King is a prominent lunar impact crater that is located on the far side of the Moon, and can not be viewed directly from Earth. The crater was named after Arthur Scott King and Edward Skinner King in 1970. Prior to that, this crater was known as Crater 211. It forms a pair with Ibn Firnas, which is only slightly larger and is attached to the northeast rim of King. To the northwest is the crater Lobachevskiy, and Guyot is located an equal distance to the north-northwest.
Lyell is a lunar impact crater that lies along the eastern edge of the Mare Tranquillitatis, at the northern arm of the bay designated Sinus Concordiae. It was named after Scottish geologist Charles Lyell. To the north along the edge of the lunar mare is the crater Franz. The region of terrain to the east of Lyell is named Palus Somni.
Condorcet is a lunar impact crater that is located in the eastern part of the Moon's near side, to the southeast of the Mare Crisium. It was named after French mathematician Marquis de Condorcet. To the northeast of Condorcet are the craters Hansen and Alhazen.
Carmichael is a lunar impact crater that is located along the eastern edge of the Sinus Amoris, in the northeastern quadrant of the Moon's near side. Its diameter is 20 km. It was named after American psychologist Leonard Carmichael. It lies within a couple of crater diameters south-southwest of the smaller crater Hill. Further to the east-northeast is the prominent crater Macrobius. Carmichael was designated Macrobius A before being given its current name by the IAU.
Gilbert is a large lunar impact crater that lies near the eastern limb of the Moon. Due to its location this feature appears foreshortened when viewed from the Earth, limiting the amount of detail that can be observed. The crater lies to the northwest of the similar-sized walled plain Kästner, to the west of the Mare Smythii.
Fredholm is a small lunar impact crater that is located in the rugged ground to the west of the Mare Crisium. It was named after Swedish mathematician Erik I. Fredholm. It was previously designated Macrobius D. It lies midway between the prominent craters Macrobius to the north and Proclus almost due south.
Esclangon is a lunar impact crater that is located in the rugged terrain to the northwest of the prominent crater Macrobius, and east of Sinus Amoris. Its diameter is 15 km. It was named after French astronomer Ernest Esclangon. This formation was previously designated Macrobius L. Just to the west-southwest is the crater Hill. Lacus Bonitatis, the Lake of Good, is located to the east and northeast of Esclangon.
Fermi is a large lunar impact crater of the category named a walled plain. It was named after Italian-American physicist and Nobel laureate Enrico Fermi. It lies on the far side of the Moon and can not be viewed from the Earth. Thus this feature must be viewed from an orbiting spacecraft.
Kästner is a lunar impact crater that is located near the eastern limb of the Moon, to the southwest of the Mare Smythii. Just to the northwest of Kästner is the walled plain Gilbert. To the south is the prominent crater Ansgarius, and to the southwest lies La Pérouse.
Weierstrass is a small lunar impact crater that is attached to the northern rim of the walled plain Gilbert, in the eastern part of the Moon. It also lies very near the crater Van Vleck, a similar formation just to the southeast that is almost attached to the outer rim. Due to its location, the crater appears foreshortened as seen from the Earth.
Van Vleck is a lunar impact crater that is located near the northeastern rim of the walled plain Gilbert, to the west of the Mare Smythii. The similar crater Weierstrass is nearly joined to the northwestern rim of Van Vleck. To the east is the small Carrillo.
Helmert is a lunar impact crater at the southern edge of the Mare Smythii. It lies near the eastern limb of the Moon, and from the Earth it is seen nearly from the side. The visibility of this feature can be strongly affected by libration of the Moon in its orbit.
Warner is a lunar impact crater that is located in the southern part of the Mare Smythii, near the eastern limb of the Moon. In this location the crater is viewed almost from the edge from Earth, and is sometimes hidden from sight due to libration. The crater lies just to the south-southeast of the very similar Runge. To the southwest is Widmannstätten, and to the south is the merged Kao–Helmert crater pair.
Erro is a lunar impact crater that lies beyond the eastern limb of the Moon, on the far side as seen from the Earth. It lies along the eastern fringes of the uneven plain that joins Mare Marginis to the northwest with Mare Smythii to the west-southwest. This part of the surface is sometimes brought into sight of observers on the Earth due to libration. However even at such times not much detail can be seen, as the surface is viewed from the edge.
Guyot is a lunar impact crater on the Moon's far side. It is separated from the crater Kostinskiy to the northeast by only a few kilometers of rough terrain. To the west-southwest lies the crater Lobachevskiy and to the east-southeast is Ostwald.
Ostwald is a lunar impact crater on the far side of the Moon. It lies just to the east of the crater Guyot, and near the northern border of Ibn Firnas. Recht lies along its eastern rim.