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Kepler's Third Law
Kepler's third law (solar units): P² = a³. Period in years, distance in AU.
Before you start
In solar units, P² = a³. Mercury is fast and close; Saturn is slow and far.
Key idea
Distance and period are locked. You do not need the planet’s mass for this law around the Sun.
What you see
- Orbit scaled by a
- Planet presets
- P² vs a³ check
Try this
- Click Mars, then Jupiter
- Try a = 4 AU — period should be 8 years
Common mistakes
- Mixing years with days, or AU with kilometres, without converting
Glossary
- AU
- Astronomical unit — Earth’s average distance from the Sun.
- Kepler III
- P² proportional to a³.