I learned that the eytmology of equinox is equi (equal) nox (night). So I would assume that the sunrise and sunset of our upcoming vernal equinox (March 21) would be at the same time (e.g. 6:05 am and 6:05 pm), which would equal 12 hours of day and night. But the rise and set on March 21 is 6:58 am and 7:10 pm. That’s about 12 hours and 12 minutes. But on March 16 sunrise and sunset was very close to being precisely 12 hours. Why is the equinox on March 21 and not on March 16?