Grimaldi is a large basin located near the western limb of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. It lies to the southwest of the

Oceanus Procellarum Oceanus Procellarum ( la, Ōceanus procellārum, lit=Ocean of Storms) is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Proc ...

, and southeast of the crater

Riccioli Giovanni Battista Riccioli, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion ...

. Between Oceanus Procellarum is Damoiseau, and to the north is Lohrmann. Hevelius crater - A

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 mare lava floor is the most notable feature of this crater, forming a flat, relatively smooth and featureless surface with a particularly low

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

. 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 174 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 (German for 'groove') is typically used to describe any of the long, narrow depressions in the surface of the Moon that resemble channels. The Latin term is ''rima'', plural ''rimae''. Typically, a rille can be several kilometers wid ...

s named the Rimae Grimaldi. To the northwest, rilles belonging to the Rimae Riccioli approach the western edge of Grimaldi's rim. A mass concentration (mascon), or gravitational high, has been identified in the center of Grimaldi (corresponding with the mare). The mascon was mapped at high resolution by

GRAIL The Gravity Recovery and Interior Laboratory (GRAIL) was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraf ...

. File:Grimaldi basin topo.jpg, Topographic map of the basin File:Grimaldi basin GRAIL gravity.jpg, Gravity map based on

Grimaldi has a history of transient lunar phenomena, including occasional flashes of light, color patches, and areas of hazy visibility. Gaseous emissions from this area have also been detected using

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

Satellite craters

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

References

* * * * * * * * * * * * {{cite book , first = Peter T. , last = Wlasuk , date = 2000 , title = Observing the Moon , publisher = Springer , isbn = 978-1-85233-193-1 Impact craters on the Moon