Orbital mechanics · d ≈ 2.44 R (ρ_M / ρ_m)^(1/3)

Roche Limit (fluid)

The distance within which a fluid satellite held together only by gravity is pulled apart by tides. Inside the Earth–Moon fluid Roche limit — about 18,000 km — a Moon-like body could not survive.

Primary radius (R⊕)Primary density (kg/m³)Satellite density (kg/m³)

Roche limit18365km

Formula: d ≈ 2.44 R (ρ_M / ρ_m)^(1/3)

Worked example

With the default inputs, roche limit (fluid) evaluates to 18365 km — Earth–Moon (fluid) → ~18,000 km. The validator recomputes this against the known value on every build, so the formula is checked, not asserted.

Highlights

›Earth–Moon: ~18,000 km

The Roche Limit

Knowledge connections

Associated withThe Roche Limit

Sources

The primary and reference sources this topic draws on.

NASANational Aeronautics and Space Administration
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