Here’s why we have leap years and other calendar names

Since Feb. 29, 2020 is leap day, let’s take a minute to talk about time.
Why we leap
Leap days keep our modern-day Gregorian calendar in alignment with Earth’s revolutions around the sun. It takes Earth 365.242189 days, or 365 days, five hours, 48 minutes and 45 seconds, to circle the sun. This is called a tropical year, and it starts on the spring equinox in March.
The modern Gregorian calendar added leap day because its precursor, the Julian calendar, did not precisely calculate th