What did you change in the model?
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.
Labs / Astronomy / Kepler's Harmonic Law
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.
Why it matters
Why explore this?
Astronomy uses patterns in light and motion to explain objects we cannot touch directly. This model lets you change one part of a space system and see what the evidence would look like.
Explore
Try the model
a 1.52 AUT 1.87 yrT²/a³ 1.000
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
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?
Explain
Make sense of what happened
Look for a cause-and-effect rule: what did you change, what responded, and what stayed the same? Astronomers use those patterns to infer how distant systems work.
Check
Before you leave
What visible evidence changed?
What rule could explain that change?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.