Labs / Astronomy
Kepler's Harmonic Law
Grab the planet and slide it toward or away from the Sun. Move it out and it slows down; pull it in and it races. The companion plot drops a point onto the T² = a³ line every time — the ratio of period-squared to axis-cubed barely budges, which is exactly what Kepler discovered.
a 1.52 AUT 1.87 yrT²/a³ 1.000
What to try
- Move the planet twice as far out. Does its year take twice as long, or more?
- Where does the moving point land relative to the straight T² = a³ line as you drag?
- Why do inner planets like Mercury whip around so much faster than outer ones?
- Watch the T²/a³ readout while you drag — what would it mean if it drifted?
- Turn on "Compare with Earth." How far out must a planet sit before its year is ten Earth-years long?