Firmicus is a lunar

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

that lies in the eastern part 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 ...

's near side, so that from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...

it appears oval in shape due to foreshortening. It is, however, very nearly circular. The crater is located to the west of the Mare Undarum, and northeast of the similar-sized crater Apollonius. To the north of Firmicus are the craters van Albada and Auzout. Attached to its northwest rim is the

Lacus Perseverantiae Lacus Perseverantiae (Latin ''persevērantiae'', "Perseverance") is a small lunar mare extending westward from the northwestern exterior of the crater Firmicus, with smaller extensions to the northeast and northwest at the eastern terminus. Its n ...

, a miniature

lunar mare The lunar maria (; singular: mare ) are large, dark, basaltic plains on Earth's Moon, formed by ancient asteroid impacts on the far side on the Moon that triggered volcanic activity on the opposite (near) side. They were dubbed , Latin for 'seas' ...

. The crater is named after 4th century Roman astrologer

Julius Firmicus Maternus __NOTOC__ Julius Firmicus Maternus was a Roman Latin writer and astrologer, who received a pagan classical education that made him conversant with Greek; he lived in the reign of Constantine I (306 to 337 AD) and his successors. His triple career ...

. The name was formally adopted by the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

in 1935. The most notable aspect of Firmicus is the dark, flat floor. It has a similar

albedo Albedo (; ) is the measure of the diffuse reflection of 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 that refl ...

to the surface of

Mare Crisium Mare Crisium (Latin ''crisium'', the "Sea of Crises") is a lunar mare located in the Moon's Crisium basin, just northeast of Mare Tranquillitatis. The basin is of the Pre-Imbrian period, 4.55 to 3.85 billion years ago. Characteristics Mare C ...

to the north, making it stand out somewhat from its surroundings. The floor has suffered no significant impacts since it was created, although there are undoubtedly many minor impacts across its surface. The outer rim of Firmicus has undergone some erosion, particularly along the northern rim where it is overlain by a pair of small craterlets.

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 Firmicus. File:Firmicus C (LROC-WAC) 2.png, Firmicus C is a concentric crater File:Firmicus C crater AS17-P-2641.jpg, Oblique view of Firmicus C from Apollo 17

References

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External links

LTO-62C1 Firmicus
— L&PI

topographic map In modern mapping, a topographic map or topographic sheet is a type of map characterized by large-scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but histori ...

{{DEFAULTSORT:Firmicus (Crater) Impact craters on the Moon