Palus Somni
Encyclopedia
Palus Somni is an area on the Moon
of relatively level but somewhat uneven terrain that lies along the northeastern edge of Mare Tranquillitatis
and the Sinus Concordiae
. It has selenographic coordinates
14.1° N, 45.0° E, and has a diameter of 143 km.
The surface of this feature has low ridges and patches of level terrain. It has a higher albedo
than the lunar mare
to the west, and is a shade of grey typical of continental terrain. A few minor craters lie within its borders, with the flooded Lyell
along the west edge, Crile
to the east, and Franz
to the northwest.
In 1907 it was described as having "a color which is unique upon the moon, a kind of light brown, quite unlike the hue of any of the other plains or mountain regions"
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
of relatively level but somewhat uneven terrain that lies along the northeastern edge of Mare Tranquillitatis
Mare Tranquillitatis
Mare Tranquillitatis is a lunar mare that sits within the Tranquillitatis basin on the Moon. The mare material within the basin consists of basalt formed in the intermediate to young age group of the Upper Imbrian epoch. The surrounding mountains are thought to be of the Lower Imbrian epoch, but...
and the Sinus Concordiae
Sinus Concordiae
Sinus Concordiae is a bay on the Moon that lies along the eastern edge of the Mare Tranquillitatis. Along its northern border is an area called the Palus Somni, while the southern border is an area of irregular terrain that contains the ruined crater Da Vinci...
. It has selenographic coordinates
Selenographic coordinates
Selenographic coordinates are used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth...
14.1° N, 45.0° E, and has a diameter of 143 km.
The surface of this feature has low ridges and patches of level terrain. It has a higher albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
than the lunar mare
Lunar mare
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...
to the west, and is a shade of grey typical of continental terrain. A few minor craters lie within its borders, with the flooded Lyell
Lyell (lunar crater)
Lyell is a lunar crater that lies along the eastern edge of the Mare Tranquillitatis, at the northern arm of the bay designated Sinus Concordiae. 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.The outer rim of this...
along the west edge, Crile
Crile (crater)
Crile is a tiny lunar crater. It is roughly circular and cup-shaped, with interior walls that slope down to the mid-point. The crater lies in the Palus Somni, between the Mare Crisium to the east and Mare Tranquillitatis to the west....
to the east, and Franz
Franz (crater)
Franz is a small lunar crater that is located along the eastern edge of the Sinus Amoris, a bay that forms a northern extension to the Mare Tranquillitatis. It lies to the southwest of the prominent crater Macrobius...
to the northwest.
In 1907 it was described as having "a color which is unique upon the moon, a kind of light brown, quite unlike the hue of any of the other plains or mountain regions"