The shortest day.

[Pete]

the sun's path? i thought we moved around the sun.... i've been lied to (now i'm fuzzy).

[Pope Urban VIII]He's a heretic! BURN HIM![/Pope Urban VIII]
Actually it's convenient sometimes to consider a frame of reference carried by the Earth as it orbits the Sun (but not rotating daily with the Earth). In that frame of reference, the Sun does indeed appear to 'orbit' the Earth once a year. Just a convenience, you understand...

Precession and nutation? Yep, they're there too, but much longer-term effects. Precession was a pig to deal with in my student days (doing the astronomy module) - forever having to correct all those f***ing RA's and decl's for J1900 and J1950 ... we didn't even have J2000 in those days, nor computers ... don't get me started (*mutter*)...

 

[on the road]

The winter solstice is 22nd at 6.08am, all that means is that the sun is at 0 degrees on the ecliptic so will be furthest south at that point, but it doesn't mean it's the shortest day due to the fact that the sun is moving eastwards in the sky as it's going from west to east. It's very difficult to work out the shortest day but it isn't always on the day of the winter solstice.