Skip to content
AsteriaStar
Orbital mechanics · r_H ≈ a (m / 3M)^(1/3)

Hill Sphere Radius

The radius within which a body's gravity dominates over the larger body it orbits — the region where its moons can hold. Earth's Hill sphere reaches about 1.5 million kilometres.

Hill radius0.010003AU

Formula: r_H ≈ a (m / 3M)^(1/3)

Worked example

With the default inputs, hill sphere radius evaluates to 0.010003 AU — Earth → ~0.01 AU (1.5 million km). The validator recomputes this against the known value on every build, so the formula is checked, not asserted.

Highlights

  • ›Earth: ~0.01 AU

The physics behind it

Knowledge connections

Sources

The primary and reference sources this topic draws on.

  • NASANational Aeronautics and Space Administration

    Mission data, planetary science, space telescopes, and public-domain imagery.

    Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.