Thirty days hath September,
April, June and November;
All the rest have thirty-one
Save February, she alone
Hath eight days and a score
Til leap year gives her one day more.
In Leap Year, there are 29 days in February.
~ ~ ~
Why do we need Leap Years?
Leap Years are necessary to keep our calendar in alignment with Earth's revolutions around the sun. It takes the Earth approximately 365.242199 days (a tropical year) to circle once around the Sun.
However, the Gregorian calendar has only 365 days in a year. If we did not add a day on February 29 nearly every 4 years, there would be a loss of almost six hours from our calendar every year. After 100 years, our calendar would be off by nearly 24 days!