Cassini (lunar crater)

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This is about the lunar crater; for the Martian one, see Cassini (Martian crater).
Cassini (LRO).png
LRO image
Coordinates 40°12′N 4°36′E / 40.2°N 4.6°E / 40.2; 4.6Coordinates: 40°12′N 4°36′E / 40.2°N 4.6°E / 40.2; 4.6
Diameter 57 km
Depth 1.2 km
Colongitude 356° at sunrise
Eponym Giovanni Cassini
Jacques Cassini

Cassini is a lunar impact crater that is located in the Palus Nebularum, at the eastern end of Mare Imbrium. The crater are named after astronomers Giovanni and Jacques Cassini. To the northeast is the Promontorium Agassiz, the southern tip of the Montes Alpes mountain range. South by south-east of Cassini is the crater Theaetetus. To the northwest is the lone peak Mons Piton.

From that location the Earth would mainly appear in the lunar sky at around 50 degrees above the southern horizon. Also the sun rises during the third quarter of Earthshine and the sun sets during its first quarter.


The floor of Cassini is flooded, and is likely as old as the surrounding mare. The surface is peppered with a multitude of impacts, including a pair of significant craters contained entirely within the rim. Cassini A is the larger of these two, and it lies just north-east of the crater center, its depth is more than 2.5 km and has the elevation of 4,487 meters below mean level. A hilly ridge area runs from this inner crater toward the south-east. Near the south-west rim of Cassini is the smaller crater Cassini B whose depth is about 2 km (elevation: -4,400 meters). These elevations were recently scanned by the Lunar Reconnaissance Orbiter.[1]

Oblique view from Apollo 15
The crater Cassini, from Lunar Reconnaissance Orbiter data. Inset graph is elevations taken across the green line, from left to right, and includes dips at the locations of subcraters Cassini B (left) and Cassini A (right).

The walls of this crater are narrow and irregular in form but remain intact despite the lava flooding. Beyond the crater rim is a significant and irregular outer rampart.

For unknown reasons, this crater was omitted from early maps of the Moon. This crater is not of recent origin, however, so the omission was most likely an error on the part of the map-makers.

Satellite craters[edit]

Cassini and its satellite craters taken from Earth in 2012 at the University of Hertfordshire's Bayfordbury Observatory with the telescopes Meade LX200 14" and Lumenera Skynyx 2-1

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Cassini.

Cassini Latitude Longitude Diameter
A 40.5° N 4.8° E 15 km
B 39.9° N 3.9° E 9 km
C 41.7° N 7.8° E 14 km
E 42.9° N 7.3° E 10 km
F 40.9° N 7.3° E 7 km
G 44.7° N 5.5° E 5 km
K 45.2° N 4.1° E 4 km
L 44.0° N 4.5° E 6 km
M 41.3° N 3.7° E 8 km
P 44.7° N 1.9° E 4 km
W 42.3° N 4.3° E 6 km
X 43.9° N 7.9° E 4 km
Y 41.9° N 2.2° E 3 km
Z 43.4° N 2.3° E 4 km

See also[edit]