Can you help me brainstorm some events that are supposed to happen on a predictable regular cycle, several years apart? In addition to:
* Leap year happens every 4 years. (US Presidential elections are in leap years.)
* You're supposed to get a tetanus booster shot every 10 years.
* Periodical cicadas emerge every 17 years.
* Halley's comet returns every 74 to 79 years.
This is for a project that I'm working on. What other cycles like this can you think of?
@frameacloud the 11 year solar activity cycle, and the 11.86 year orbital period of jupiter comes to mind
also in astronomy, precession of the equinoxes is on a 25772 year cycle
astronomy is a good source for long-period predictable cycles
in addition to 17 year cicadas, there are also 11 and 13 year cicadas, and probably some of other primes too
you get a new credit/debit card every five years, when the old one expires
@frameacloud someone liked this and i looked at it again and thought "wow that's a really mundane thing to end on after talking about astronomy"
