Equations
Kepler's third law (circular orbit)
Gravitation · id kepler_third_law
T^2 = \frac{4 \pi^2 r^3}{G M}
| Symbol | Quantity | Unit | Meaning | Usual range |
|---|---|---|---|---|
T | orbital period | s | Time for one orbit | 1 to 1e+12 |
r | orbital radius | m | Radius of the orbit | 1 to 1e+14 |
G | gravitational constant | m^3/(kg*s^2) | Newton's constant of gravitation | |
M | central mass | kg | Mass of the central body | 1 to 1e+32 |
Assumptions
- Circular orbit
- Orbiting body much lighter than the central body
Valid when
- Speeds far below the speed of light
Found by
Questions with these words retrieve this equation: kepler, orbital period, orbit, year, satellite, planet, how long to orbit.
Source
OpenStax University Physics Volume 1, Chapter 13 (reference; entry written by the project). License: MIT. Entry confidence: 0.99.