Just in case you’re interested (and, as i’m curious myself) here’s a few facts about leap years:
Why do we need leap years?
The solar year, also called the tropical year, is the time it takes for the earth to perform one revolution around the sun (~365 days).
The length of a day and the solar year do not divide evenly, gradually this leads to a loss of around 1 day in every 4 years.
We need leap years to synchronise the calendar year back to the solar year, this is achieved by adding a leap day (February 29th) into a leap year.
How do we know which year is a leap year?
Leap years are years that are divisible by 4 and not divisible by 100 (unless they are also divisible by 400).
This link has an excellent explanation as to why, if you wish to procrastinate further. Happy Leap Year!
