Unlocking the Cosmos
A deep dive into Kepler's Third Law, the fundamental principle governing planetary motion. Witness the harmony of the spheres through interactive visuals and real-world data.
Interactive Simulation
Adjust the slider to change the planet's semi-major axis and observe the effect on its orbital period, just as Kepler described.
1.00 AU
Calculated using P² ≈ a³
The Law of Harmonies
Kepler's Third Law provides a mathematical relationship between a planet's orbital period and its distance from the star.
P (Orbital Period)
The time it takes for a planet to complete one full orbit around its star. Usually measured in Earth years.
a (Semi-Major Axis)
Half of the longest diameter of the elliptical orbit. It represents the planet's average distance from its star, measured in Astronomical Units (AU).
Real-World Examples
See how Kepler's Third Law applies to the planets in our own solar system. The calculated period closely matches the actual observed period.
| Planet | Semi-Major Axis (a) (AU) | Orbital Period (P) (Years) | Calculated Period (√a³) |
|---|---|---|---|
| Mercury | 0.39 | 0.24 | 0.24 |
| Venus | 0.72 | 0.61 | 0.61 |
| Earth | 1.00 | 1.00 | 1.00 |
| Mars | 1.52 | 1.88 | 1.87 |
| Jupiter | 5.20 | 11.86 | 11.86 |
| Saturn | 9.58 | 29.46 | 29.65 |
| Uranus | 19.22 | 84.01 | 84.26 |
| Neptune | 30.05 | 164.80 | 164.73 |
A Revolutionary Discovery
Journey back in time to understand the genius of Johannes Kepler and the scientific revolution his work ignited.
