Feb. 29 is returning to our calendars for the first time since 2016. Adding an extra day is known as a leap year, a corrective measure that keeps our calendar synchronized with the seasonal year.
It takes earth 365.242189 days to orbit the sun. The extra day is needed so that we don’t eventually celebrate Christmas in summer. Three criteria must be met for a year to be a leap year:
• The year must be evenly divisible by four.
• The year is also evenly divisible by 400.
• But if it can also be divided by 100, it is not a leap year.