**Neumayer (crater)**
**Definition:**
Neumayer is a lunar impact crater located near the Moon’s southeastern limb, characterized by its worn and eroded rim and a relatively flat interior floor. It is named after the German geophysicist Georg von Neumayer.
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# Neumayer (crater)
## Overview
Neumayer is a prominent lunar impact crater situated near the southeastern limb of the Moon. Due to its location, it appears foreshortened when viewed from Earth, making detailed observation challenging. The crater is notable for its heavily eroded and irregular rim, which has been significantly worn down by subsequent impacts and geological processes. Its interior floor is relatively flat and marked by several smaller craters and features indicative of the Moon’s complex impact history.
The crater is named in honor of Georg von Neumayer (1826–1909), a German geophysicist and polar researcher who made significant contributions to the study of Earth’s magnetism and meteorology.
## Location and Surroundings
Neumayer lies near the southeastern limb of the Moon, positioned at selenographic coordinates approximately 72°S latitude and 84°E longitude. This location places it close to the lunar south pole, in a region characterized by rugged terrain and numerous overlapping craters.
### Nearby Features
– **Bailly Crater:** To the northwest of Neumayer lies Bailly, one of the largest craters on the near side of the Moon, notable for its vast size and heavily eroded walls.
– **Boguslawsky Crater:** Located to the northeast, Boguslawsky is a large, ancient crater with a worn rim.
– **Phocylides Crater:** Situated to the west-northwest, Phocylides is a large, irregular crater with a relatively flat floor.
– **Wargentin Crater:** To the north, Wargentin is a unique crater filled with solidified lava, giving it a distinctive appearance.
The region surrounding Neumayer is marked by a high density of impact craters, many of which overlap or intrude upon one another, reflecting the Moon’s long history of bombardment.
## Physical Characteristics
### Dimensions
Neumayer has a diameter of approximately 70 kilometers and a depth estimated at around 3.0 kilometers. Its size classifies it as a large lunar crater, though it is smaller than some of the nearby giant craters such as Bailly.
### Rim and Walls
The crater’s rim is heavily degraded and irregular, with numerous smaller craters superimposed upon it. The original sharpness of the rim has been softened by erosion processes, including micrometeorite impacts and seismic shaking caused by nearby impacts. The rim is not uniformly circular; it exhibits bulges and indentations, particularly on the northern and eastern sides, where it has been breached by subsequent impacts.
### Interior Floor
The floor of Neumayer is relatively flat compared to the surrounding rugged terrain. This flatness is likely due to the settling of impact melt and the accumulation of regolith over time. Several small craters dot the interior, including a notable crater near the center, which may be a secondary impact feature.
The floor lacks significant central peaks, which are common in craters of similar size, possibly due to the crater’s age and the degree of erosion it has undergone.
### Geological Features
– **Impact Ejecta:** Surrounding Neumayer is a blanket of ejecta material, consisting of fragmented rock and dust thrown out during the crater-forming impact.
– **Secondary Craters:** Numerous smaller craters in the vicinity are likely secondary impacts resulting from debris ejected during the formation of Neumayer and nearby craters.
– **Regolith Layer:** The surface is covered by a layer of lunar regolith, a fine, powdery soil formed by continuous meteoroid bombardment.
## Formation and Age
Neumayer is classified as an ancient impact crater, formed during the Pre-Nectarian or Nectarian period of lunar history, approximately 3.9 to 4.1 billion years ago. This age is inferred from the crater’s heavily eroded state and the density of superimposed craters.
The crater was created by the high-velocity impact of an asteroid or comet, which excavated a large cavity in the lunar crust. The impact generated shock waves that fractured the surrounding rock and melted material, some of which settled on the crater floor as impact melt.
## Observation and Exploration
### Visibility from Earth
Due to its location near the lunar limb, Neumayer is subject to libration effects, which cause it to sometimes be more visible and at other times partially hidden from Earth-based observers. When conditions are favorable, it can be observed with moderate-sized telescopes, though its foreshortened appearance limits detailed study.
### Lunar Missions
Neumayer has been imaged by various lunar missions, including the Lunar Reconnaissance Orbiter (LRO), which has provided high-resolution photographs and topographic data. These images have allowed scientists to study the crater’s morphology and geological context in greater detail.
No lander or rover missions have directly targeted Neumayer, but its proximity to the lunar south pole region makes it of interest for future exploration, particularly in the context of understanding the geology of the lunar limb and polar areas.
## Scientific Significance
Neumayer serves as an important site for studying the processes of impact cratering and lunar geological evolution. Its heavily eroded rim and relatively flat floor provide insights into the long-term effects of space weathering and impact degradation on lunar surface features.
The crater’s location near the lunar south pole also makes it relevant for understanding the distribution of impact craters in polar regions, which are of interest due to the potential presence of water ice in permanently shadowed areas nearby.
## Nomenclature
The crater was officially named „Neumayer” by the International Astronomical Union (IAU) in recognition of Georg von Neumayer’s contributions to geophysics and polar research. The naming follows the convention of assigning lunar craters the names of deceased scientists and explorers who have made significant contributions to their fields.
## Summary
Neumayer is a large, ancient lunar impact crater near the Moon’s southeastern limb, characterized by a worn and irregular rim and a relatively flat interior floor. Its geological features and location make it a subject of interest for lunar scientists studying impact processes and the Moon’s polar regions. Although challenging to observe from Earth, modern lunar missions have provided detailed imagery that continues to enhance understanding of this crater’s formation and evolution.
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**Meta Description:**
Neumayer is a large, ancient lunar impact crater near the Moon’s southeastern limb, notable for its eroded rim and flat floor. It offers valuable insights into lunar geology and impact history.