A Crisp Ring-Plain on the Edge of Mare Frigoris

Feature Profile & Selenographic Data

Feature type

crater

Coordinates

62.31° N · 34.99° E

Diameter

37.78 km

IAU approval

1935/01/01 00:00:00

LAC quadrangle

LAC-13 · Aristoteles

Geological Chronicle

Democritus lies on the northern part of the Moon, just to the north of Mare Frigoris and the lava-flooded crater Gärtner. Measuring 37.78 kilometers in diameter, the formation was described by T. W. Webb as a deep ring-plain.

Directly north of the feature sits Arnold, another flooded crater, but Democritus itself displays a sharp-edged rim with little sign of erosion. Outward notch-like bulges give it a slightly irregular shape, while single or double terraces line inner walls that lead down to a relatively flat floor with a small central peak.

The crater was named after the ancient Greek philosopher Democritus. Giovanni Riccioli introduced the name in his 1651 nomenclature system, supplanting earlier designations from Michael van Langren and Johannes Hevelius before the International Astronomical Union formally adopted it in 1935.

Chronology & Exploration

1. 1645 Van Langren Map

   Michael van Langren's map designates the crater Alfonsi IX Reg. Cast.

2. 1651 Riccioli Nomenclature

   Giovanni Riccioli introduces the name Democritus in his lunar nomenclature system.

3. 1935 IAU Formal Adoption

   The International Astronomical Union formally adopts the designation Democritus.

Scientific Sources & References

• IAU Gazetteer of Planetary Nomenclature — Official feature coordinates and dimensions
• Wikipedia (en) — Extracted text covering physical morphology, naming history, and satellite crater details

Name Origin

Greek astronomer, philosopher (c. 460-360 B.C.).