... Leap Year ...
It takes the Earth approximately 365.242189 days
(or 365 days, 5 hours, 48 minutes, and 45 seconds)
to circle once around the Sun (our closest star).
This is called a tropical year, and is measured from the March
However, the Gregorian calendar (the one we use)has only 365 days in a
so if we didn't add a leap day on February 29 nearly every four years,
we would lose almost six hours off our calendar every year.
After only 100 years, our calendar would be off by around 24 days
and we just can't have that!