Did you know that the word "month" is derived from the word "moon?" Yes, our months are intended to emulate lunar cycles. Except, peculiarly, the moon completes 13 orbits around the earth annually, 28 days each, with 2.2 days to catch up because we, earth as a whole, move very quickly. Yet we've chosen to design our entire year around 12 months. Oct means 8, that's month 10, Nov is 9, month 11, and Dec is 10, month 12. 8 is 10, 9 is 11, and 10 is 12. Just a mess. Our Gregorian calendar is off by one day every 3216 years, while the lunar calendar is only off one day every 31,250 years. 10 times more accurate. The point of us sharing this with you is simply to inform you that nobody really knows what year it is. But, it's probably something like 4,537,999,042.
Every year, from the perspective of living beings on the northern hemisphere, the winter solstice, usually December 21st or 22nd, marks a turning point in the orbit of our tiny blue home. Though we are approximately 1 million miles closer to the sun in December than the 93 million mile average, at this point in our orbit, we northern hemisphere folks are also tilted 23.5 degrees AWAY from the sun and it can't quite reach us over the north pole the way it does in July, so it appears to be on a well deserved, though very inconvenient, vacation. 
After 3 days in this minor depression, ending December 24th or 25th, The sun, reborn and with a rejuvenated sense of moxy, finds it ought to get out of bed and begin the trek back over the north pole. With this, the days begin to grow longer and we celebrate this newborn sun — welcoming it with trees and lots of pretty lights, to remind it just what we'd like it to do for us: bring spring as it has for the past 4 and a half billion years, but employees can be quite forgetful and it's important to keep them reminded of what it is they're meant to be doing at any given time. Any distractions, a SnapChat from Uncle Josephine, for example, can result in a considerable loss in productivity. 
Most importantly, so far it's been working! The sun seems to respond quite well to our little light shows and that is the beauty of it. It inspires a sense of magic, deep contentment, and pure joy in all of our hearts to know that, though this technically signifies the first day of winter, spring is on its way! So, we shower each other with cookies, gifts and good company, celebrate the coming of another year in the life of our tiny blue home, and keep a watchful eye on the sun to ensure it continues to show up for work.
We at The Hitchhiker's Guide to Peace happen to be of the opinion that Christmas is very nice. We agree that we cannot call it our favorite time of year. We're quite fond of growing things here, so if you'd all help light up some more trees and brighten your Christmas spirit, we may be able to convince the sun to start bringing spring just a little sooner. But, still very nice.