Yeah ... 'Happy Sun-sun' is a bit wtf. 'Happy Closest-standing' at least alludes to why the time is special. BUT, has lost its stellar significance.
Periheliostice? Solperistice? Northern Kiss?
Well, at least "closest-standing" is suggesting the event is related to something. Ellipsis is a perfectly sound process when it eludes the appropriate elements out of the explicitly uttered expression.