Fun facts about leap years

This Thursday, Feb. 29, is leap day. You might know that a leap year generally occurs every four years, but you might not know the reason for this rule or that there is an exception to it.

Keep reading for fun facts about leap years.

Why do we have leap years?

The 365 days of a regular calendar year is actually an approximation of the time it takes the Earth to orbit the sun. According to NASA, it takes approximately 365.25 days for Earth to complete a full orbit around the Sun. Since it’s hard to add a quarter of a day into a calendar every year, we round down to 365 days per year, and extra hours from each regular year get added up into a leap day that occurs every four years. In other words, leap years keep the calendar lined up with the Earth’s actual orbit.

Which years are leap years?

Leap years generally occur on any year that is divisible by four. For example, 2024 is divisible by four, so it is a leap year. However, 2025, 2026 and 2027 are not divisible by four, so they are regular years. This rule was created when the Julian calendar came into use in Ancient Rome.

However, when the western world switched to the Gregorian calendar in the late 16th Century, an exception to the four year rule was introduced. Because it takes slightly less than 365.25 days for Earth to orbit the Sun, having leap years every four years with no breaks would actually push the calendar out of sync with the seasons after a couple of centuries. To keep the calendar accurate, years divisible by 100 but not by 400 are not leap years. That means that 2100, 2200 and 2300 will have 365 days, but 2400 will have 366 days.

Spend the leap day wisely, Bruins — the next one won’t come for another four years!