Hello,
From what I've read recently, there are three variants of an equinox:
- Modern astronomical definition: apparent geocentric longitude of the
sun is 0 or 180 degrees.
- The older astronomical definition (often used in dialling) : solar
declination is 0 degrees.
- 'Temporal equinox': halfway between solstices as measured by passage
of time, which is the lay/folk/traditional understanding
I'd like to know:
How big are the time intervals between these three types of equinoxes?
How much do these intervals change as the years or centuries go by, if
at all?
Thanks,
Steve
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