What caused the change?
Labs / History
Calendar Gears
Twelve lunar months come up about eleven days short of a solar year, so a moon calendar slowly slides through the seasons. Turn the crank to run time forward, then add leap months and watch the calendar new year creep back toward spring — until the 19-year Metonic cycle locks the moon and sun back into step.
Labs / History / Calendar Gears
Calendar Gears
Twelve lunar months come up about eleven days short of a solar year, so a moon calendar slowly slides through the seasons. Turn the crank to run time forward, then add leap months and watch the calendar new year creep back toward spring — until the 19-year Metonic cycle locks the moon and sun back into step.
Why it matters
Why explore this?
History is about change over time and the choices that shape it. This model helps you compare causes, consequences, and patterns without treating the past as a list of dates.
Explore
Try the model
Year 1Month 1/12Season offset +0.0 dCycle 0.0 d/19yr
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- With the pure-lunar scheme, where does the new year end up after ten years — still in spring, or a whole season away?
- How many leap months per 19 years does it take before the gold new-year dots stop wandering and cluster in one spot?
- At the Metonic setting, what does the “Cycle” readout say — how many days does the calendar slip across an entire 19-year cycle?
- Turn on the leap day. Does it help a lunar calendar, or does stacking it on top of the Metonic scheme push the alignment back off?
- Why does a 13-month year appear only sometimes, and what happens to the “season offset” the moment one is inserted?
Explain
Make sense of what happened
Build an explanation with a cause, a change, and a consequence. Then identify evidence from the model and one limitation of what the model can show.
Check
Before you leave
Who or what was affected?
What can this model not tell us?
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.