Get ready to question everything you know about leap years.

We all understand the basic rules for how we measure time. We know there are 24 hours in a day, seven days in a week, and 365 days in a non-leap year, jumping to 366 days every four years – a pattern we all learned as children.

But what if these rules weren’t entirely true?

You likely will have learned at school that leap years are necessary because the Earth’s orbit around the sun takes slightly longer than 365 days and that to…