On Mar 19, 11:40*am, "Jack )"
wrote:
"Equation of time" is the thing to plug into google,
I must do that sometime and try and get my head around what is going on
with the equinox, day lengths and when sunrise/sunset happen.

"Equation of time" has NOTHING to do with refraction but is a result
of the ellipticity of the Earth's orbit.

Jack

And the tilt of the earth's axis. The two effects are about
equal but the axial tilt effect has a period of 6 months whereas the
eccentricity effect has a period of one year.

Tudor Hughes, Warlingham, Surrey.