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?
In: Geology
First off the Equinox is actually the 19th or 20th this year (depending on which time zone you’re in).
If you were going with the eytmology you would say that the equinox is the day when day and night are (about) the same length everywhere on the planet.
Scientifically the Equinox is when the plane of the earths equator passes through the center of the sun. The effect of this is that it is the day where the sun rises directly east and sets directly west on the horizon. As for why the day isn’t exactly split between day and night there are several contributing factors to this. Two being the fact that the sun isn’t a point, and that the atmosphere will bend light a little so that where the sun appears to be isn’t quite where it is.
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