Jansen (crater)
Encyclopedia
Jansen is lunar
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...

 crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 in the north part of the 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...

. It is located to the east-southeast of the crater Plinius
Plinius (crater)
Plinius is a prominent lunar impact crater on the border between Mare Serenitatis to the north and Mare Tranquilitatis to the south. South-southeast of Plinius is the crater Ross, and to the northeast is Dawes. Just to the north is a system of rilles named the Rimae Plinius...

. The rim of Jansen is low and narrow, with a notch along the western edge. The interior is relatively level, which may indicate it has been covered by lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

. To the south-southwest a small but prominent crater lies on the crater floor, halfway between the center and the rim.

To the northwest of the rim is a rille
Rille
Rille is typically used to describe any of the long, narrow depressions in the lunar surface that resemble channels. Typically a rille can be up to several kilometers wide and hundreds of kilometers in length...

 named Rima Jansen, and to the east are wrinkle ridges in the 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...

 surface. A low ridge runs from near the southeast rim in a southeasterly direction.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Jansen.
Jansen Latitude Longitude Diameter
D 15.7° N 28.4° E 7 km
E 14.5° N 27.8° E 7 km
G 9.3° N 26.0° E 6 km
H 11.4° N 28.4° E 7 km
K 11.5° N 29.7° E 6 km
L 14.7° N 30.1° E 7 km
R 15.2° N 28.8° E 25 km
T 11.4° N 33.5° E 5 km
U 11.9° N 32.3° E 4 km
W 10.2° N 29.5° E 3 km
Y 13.4° N 28.6° E 4 km


The following craters have been renamed by the IAU
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

.
  • Jansen B — See Carrel
    Carrel (crater)
    Carrel is a small lunar crater on the Mare Tranquillitatis. It has a somewhat distorted appearance, having a slight protruding bulge in the northwest rim. The interior is somewhat irregular, with ridges and some slumped material...

    .
  • Jansen C — See Beketov
    Beketov (crater)
    Beketov is a small lunar crater that lies in the northern reaches of the Mare Tranquillitatis. To the south is the ghost crater Jansen R. Northeast of Beketov, along the edge of the mare, is the crater Vitruvius. Beketov was previously designated Jansen C before being named by the IAU. The flooded...

    .
  • Jansen F — See Cajal
    Cajal (crater)
    Cajal is a tiny lunar impact crater on the northern part of the Mare Tranquilitatis, in memory of the spanish doctor and nobel prizes Santiago Ramón y Cajal. It is a circular, cup-shaped formation that lies to the southeast of the lava-inundated crater Jansen. Also to the northwest is a system of...

    .
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