Kepler's Third Law (Periodic Law) Calculator

Kepler's Third Law of Planetary Motion

Gravitational Constant (G) = 6.6726 x 10-11N-m2/kg2
I want to calculate
Satellite orbit average radius (r) = m
Planet mass (M) = kg
Satellite orbit period (T) = s
 

What is Kepler's Third Law (Periodic Law) Calculator?

A Kepler's Third Law Calculator helps compute the relationship between the orbital period and the semi-major axis of a planet's orbit around a star. It is based on Kepler’s Third Law, which states:

where:

  • T = Orbital period (time to complete one orbit)
  • a = Semi-major axis (average distance from the star)
  • k = Constant based on the mass of the central star

For two objects orbiting the same star:

Why Use It?

  • To compare planets’ orbital periods and distances.
  • Useful in astronomy for studying celestial mechanics.
  • Helps in satellite and space mission planning.

How Does It Work?

  1. Input: Orbital period or semi-major axis of a planet.
  2. Apply Kepler’s Law: Solve for the unknown value.
  3. Output: The missing orbital period or distance.

When to Use It?

  • Studying planetary orbits.
  • Designing spacecraft trajectories.
  • Comparing exoplanet data with our solar system.