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Kepler's third law relates orbital period to orbital distance. It explains why planets farther from the Sun take longer to orbit.

Formel

The calculator applies T² = (4π² / GM) × a³
GM
GM value — Variable used in the calculation

Trin-for-trin guide

  1. 1Enter orbital period and distance, or the central body's mass
  2. 2The calculator applies T² = (4π² / GM) × a³
  3. 3Results show orbital relationship

Løste eksempler

Input
a = 1 AU (Earth orbit), M = 1.989 × 10³⁰ kg (Sun)
Resultat
T ≈ 1 year
By definition

Almindelige fejl at undgå

  • Using incorrect AU values or unit conversions
  • Confusing period with frequency

Ofte stillede spørgsmål

Does Kepler's law apply to all objects?

Yes, it applies to any orbit around a massive central body, from planets around stars to satellites around planets.

Why is period proportional to distance to the 3/2 power?

Gravity weakens with distance, requiring slower speeds at greater distances, which more than compensates for longer path length.

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