
Leap years are needed to keep our modern day Gregorian calendar in alignment with the Earth's revolutions around the sun.It takes the Earth approximately 365.242189 days – or 365 days, 5 hours, 48 minutes, and 45 seconds – to circle once around the Sun. This is called a tropical year, and is measured from the March equinox.However, the Gregorian calendar has only 365 days in a year, so if we didn't...