We celebrate John the Baptist's feast day June 24th because we know he was conceived 6 months before Christ.
Nothing earth-shattering there.
But last week I heard the relation to the solstices for the first time. (Bear with me if I'm the last to figure this out!)
John's feast day is very close to the summer solstice - the longest, brightest day of the year in the northern hemisphere. There are many analogies one can draw from that (ie, John blazed the path to Jesus, shone the light towards Him, etc).
But ironically (or planned?), just as John said he must decrease - so Jesus could increase - each day after the summer solstice gets a bit shorter and a bit darker.
Until, of course, we get to the winter solstice, which ironically (or planned?) is right about when we celebrate the birth of our Savior.
After that, every day gets a bit longer and a bit brighter!