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Leap Day…Why Does It Exist?
Once every four years, an extra calendar day is added: a leap day. But why?
The reason for adding leap days to the calendar is to align the calendar year with the actual year – which is defined by the time it takes Earth to circle the sun. It is equal to 365 days, 5 hours, 48 minutes and 46 seconds, or 365.24219 days.
If all calendar years contained exactly 365 days, they would drift from the actual year by about 1 day every 4 years. Eventually, July would occur during the northern hemisphere winter! Wouldn’t that be weird?
To correct (approximately), we add 1 day every 4 years...resulting in a leap year.
By making most years 365 days but every fourth year 366 days, the calendar year and the actual year remain more nearly in step.
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