Lunar constants and units

These are the main reference values used across Lunar Probe's calculators and explainers. Each value retains its source and an interpretation note so a rounded educational constant is not mistaken for a universal exact quantity.

Mean Radius Km

1737.4

Mean radius used for educational calculations.

Source

Diameter Km

3474.8

Twice the adopted mean radius.

Source

Surface Gravity M S2

1.62

Representative average surface gravity.

Source

Gm Km3 S2

4902.800118

Standard gravitational parameter used by the orbit simulator.

Source

Sidereal Rotation Days

27.321661

Rotation relative to the stars.

Source

Synodic Month Days

29.530588853

Mean phase cycle used by phase tools.

Source

Mean Earth Distance Km

384400

Rounded mean centre-to-centre distance; actual distance varies.

Source

Escape Velocity Km S

2.38

Representative lunar surface escape speed.

Source

Why some values are approximate

The Moon is not a perfect sphere and its distance from Earth changes continuously. Surface gravity also varies slightly with location and altitude. Tools that need a representative value use an explicitly documented average or standard constant rather than hiding the assumption.

Common units used on Lunar Probe