West crater is a small crater in

Mare Tranquillitatis Mare Tranquillitatis (Latin ''tranquillitātis'', the Sea of Tranquillity or Sea of Tranquility; see spelling differences) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It is the first location on another world to be ...

on 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 ...

, east of the

Apollo 11 Apollo 11 (July 16–24, 1969) was the American spaceflight that first landed humans on the Moon. Commander Neil Armstrong and lunar module pilot Buzz Aldrin landed the Apollo Lunar Module ''Eagle'' on July 20, 1969, at 20:17 UTC, an ...

landing site, which is known as

Tranquility Base Tranquility Base ( la, Statio Tranquillitatis) is the site on the Moon where, in July 1969, humans landed and walked on a celestial body other than Earth for the first time. On July 20, 1969, Apollo 11 crewmembers Neil Armstrong and Buzz Aldrin ...

. The name of the crater 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 1973. The Apollo 11 astronauts

Neil Armstrong Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who became the first person to walk on the Moon in 1969. He was also a naval aviator, test pilot, and university professor. ...

and

Buzz Aldrin Buzz Aldrin (; born Edwin Eugene Aldrin Jr.; January 20, 1930) is an American former astronaut, engineer and fighter pilot. He made three spacewalks as pilot of the 1966 Gemini 12 mission. As the Lunar Module ''Eagle'' pilot on the 1969 A ...

landed the

Lunar Module The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...

(LM) ''Eagle'' approximately 550 meters west of West crater on July 20, 1969. During the descent, West crater was a major landmark. The lunar lander flew over the crater at an altitude of about 100 meters. The boulder field that Armstrong saw a need to avoid during the descent was the

ejecta Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials (tephra) that came out of a volcanic explosion and magma ...

of West crater. Just beyond this ejecta was Little West crater which also had to be avoided. At the time of Apollo 11, the words “east” and “west” were used to describe directions on the Moon from the perspective of an observer on Earth. The crater was therefore named “West Crater” even though it appears to the east of the landing site on modern lunar maps.
''Apollo 11 Lunar Surface Journal'', EASEP Deployment and Closeout

References

{{reflist Impact craters on the Moon Apollo 11