At that point of the year, it is the longest night in the northern hemisphere, with the sun reaching the lowest point on the sky. After this, the days slowly get longer again. This marks the beginning of the winter. And the worse the snow and wheather was so far, the more this point has been celebrated! But for what's going on in the sky it's better to let the experts at space.com explain it.
Anyway it was usually seen as a "healing moment", where new things are being born, or old ones being cleaned. Energy and life is preparing to grow again for the next springtime. It was something of life importance...since there were no supermarkets, or central heatings and the like... There was the habbit of giving presents to each other, which is even a habit nowadays! (Just that it's called christmas now, or x-mas, for the even younger ones.)
For more information:
wikipedia.org - usually your friend
A little history of Yule
For the curious
winter solar solstice 2012
As for the "End of the World" and "Apocalypse"....who knows.... let's wait and find out! Ehehehe.
But here is some music for you to enjoy...and for the "Abwarten and Tee trinken" (Waiting and driking tea).