An Early Imbrian crater on the lunar far side

Feature Profile & Selenographic Data

Feature type

crater

Coordinates

23.51° S · 111.11° E

Diameter

111.44 km

IAU approval

1970/01/01 00:00:00

LAC quadrangle

LAC-101 · Fermi

Geological Period

Early Imbrian

Geological Chronicle

Alden is a lunar impact crater on the far side of the Moon, situated in the Fermi quadrangle between Hilbert to the north-northwest and Milne to the south-southeast. To the south-southwest lies Scaliger. The feature measures 111.44 km across.

The formation dates from the Early Imbrian period on the lunar geologic timescale. Its rim is low, worn, and eroded, especially along the southern wall. The floor is somewhat irregular and pitted. In the north and northeast, the rim is overlain by Alden C and the smaller Alden E, while the small crater Alden V lies just inside the north rim and is attached to Alden C to the east.

During planning for the Apollo 8 mission that circled the Moon, the crater was informally referred to as 'See'. The International Astronomical Union formally adopted the name Alden in 1970, honoring American astronomer Harold Lee Alden.

Chronology & Exploration

1. Early Imbrian Crater formation

   Alden dates from the Early Imbrian period on the lunar geologic timescale.

2. Apollo 8 planning Informal mission name

   During planning for the Apollo 8 mission that circled the Moon, this crater was informally referred to as 'See'.

3. 1970 IAU naming

   The International Astronomical Union formally adopted the name for American astronomer Harold Lee Alden.

Scientific Sources & References

• IAU Gazetteer of Planetary Nomenclature — Feature coordinates, 111.44 km diameter, Fermi quadrangle code, approval date, and namesake details.
• Wikipedia (en) — Description of crater location, Early Imbrian age, rim erosion, interior floor, satellite craters, Apollo 8 planning name, and namesake.

Name Origin

Harold Lee; American astronomer (1890-1964).