Grimaldi (crater)
Encyclopedia
Grimaldi is a large basin located near the western limb of the Moon
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...

. It lies to the southwest of the Oceanus Procellarum
Oceanus Procellarum
Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Earth's Moon. Its name derives from the old superstition that its appearance during the second quarter heralded bad weather...

, and southeast of the crater Riccioli
Riccioli (crater)
Riccioli is a large lunar impact crater located near the western limb of the Moon. It lies just to the northwest of the even larger and more prominent crater Grimaldi. To the southwest are the craters Hartwig and Schlüter that lie on the northeastern edge of Montes Cordillera, the ring-shaped range...

. Between Oceanus Procellarum is Damoiseau
Damoiseau (crater)
Damoiseau is a lunar crater that is located just to the west of the Oceanus Procellarum, in the western part of the Moon's near side. It lies due east of the prominent crater Grimaldi, a walled plain with a distinctive dark floor...

, and to the north is Lohrmann
Lohrmann (crater)
Lohrmann is a small lunar crater that is located to the west of the Oceanus Procellarum, near the western limb of the Moon. It lies to the north of the dark-floored walled plain Grimaldi, and just to the south of the crater Hevelius....

.

The inner wall of Grimaldi has been so heavily worn and eroded by subsequent impacts that it forms a low, irregular ring of hills, ridges and peaks, rather than a typical crater rim. However there are peaks remaining that reach heights of over 2 kilometers. The floor is the most notable feature of this crater, forming a flat, relatively smooth and featureless surface with a particularly low 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...

. The dark shade of the floor contrasts with the brighter surroundings, making the crater easy to locate. The approximate diameter of the inner rim is 140 kilometers.

Beyond the basin are the scattered remnants of an outer wall, which has a diameter of 220 kilometers. This exterior rim is more intact to the north and west of the crater than elsewhere. To the southeast of Grimaldi is a system of 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...

s named the Rimae Grimaldi. To the northwest, rilles belonging to the Rimae Riccioli approach the western edge of Grimaldi’s rim.

Grimaldi has a history of transient lunar phenomena
Transient lunar phenomenon
A transient lunar phenomenon , or lunar transient phenomenon , is a short-lived light, color, or change in appearance on the lunar surface....

, including occasional flashes of light, color patches, and areas of hazy visibility. Gaseous emissions from this area have also been detected using spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

. Orbiting spacecraft have also detected a mass concentration (mascon) below this feature.

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 Grimaldi.
Grimaldi Latitude Longitude Diameter
A 5.4° S 71.2° W 15 km
B 2.9° S 69.2° W 22 km
C 2.6° S 61.5° W 10 km
D 3.7° S 65.5° W 22 km
E 3.7° S 64.4° W 13 km
F 4.0° S 62.7° W 29 km
G 7.4° S 64.9° W 13 km
H 4.9° S 71.4° W 9 km
J 2.9° S 70.6° W 16 km
L 8.5° S 66.7° W 19 km
M 8.0° S 67.0° W 18 km
N 7.6° S 66.6° W 8 km
P 8.0° S 68.3° W 10 km
Q 4.8° S 64.8° W 21 km
R 8.5° S 71.2° W 9 km
S 6.4° S 65.0° W 11 km
T 7.7° S 70.9° W 12 km
X 5.8° S 72.3° W 9 km
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK