Orbital mechanics · T = 2π √(a³ / GM)
Orbital Period (Kepler's Third Law)
Kepler's third law: the time to complete one orbit, from the semi-major axis and the central mass. A planet at 1 AU around the Sun takes one year.
Orbital period0.99989yr
Formula: T = 2π √(a³ / GM)
Worked example
With the default inputs, orbital period (kepler's third law) evaluates to 0.99989 yr — 1 AU around 1 M☉ → 1 year. The validator recomputes this against the known value on every build, so the formula is checked, not asserted.
Highlights
- ›1 AU / 1 M☉ → 1 year
The physics behind it
Knowledge connections
- Associated withKepler's Laws of Planetary Motion
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.