Happy Leap Day

We’ve always been told that the reason for Leap Years is that the earth takes 365.25 days to orbit the sun. So every 4 years we have to add a day to the calendar to keep it in line. That is all roughly true, but not exactly…

The earth actually takes 365.2422 days to orbit the sun. In order to make up for this slight difference, we occasionally skip a Leap Year. How occasionally? Three times every 400 years. So over a 400 year stretch, we have 97 Leap Years instead of 100, which keeps the calendar in check.