The Night of Yalda
This ancient holiday dates back to Zoroastrian times, and is celebrated through rejoicing with family and friends. Every Yalda party will likely have plenty of watermelon and pomegranate in stock, with the latter symbolizing liveliness and joy, and the former is thought to keep people healthy during the winter season.
When I got home last night, I heard our neighbors' music and clapping continue on until at least 2:30 a.m. That has got to be the latest partying I've ever encountered in Iran.
Iran Daily (Dec. 21) reports that Yalda represents the birth of the Zoroastrian goddess Mitra as well as of Jesus Christ:
...the Europeans used to celebrate Yalda, but, after Christianity replaced Mehr customs, Christian leaders found out that it was impossible to ignore Mehr as its memory lived on among the people. So they decided to replace the celebration of birthday of Mehr (sun) by celebrating the brith of Jesus Christ (PBUH) on December 25. There is a slight gap between Yalda festivity and Christ's birthday owning to miscalculation in the calendar. In fact the birthday of Jesus Christ (PBUH) is on the same day as followers of Mehr customs celebrate Yalda festivity....
According to Iranian mythology, Yalda festivity is the culmination of conflict between light and dark (Ahura and Ahriman). Ahriman enjoys the longest night and the darkness of the night in the conflict, but, the light came out victorious in the struggle and the Sun was born. After the birth of the Sun, the day (light) gradually became longer from the minimum at the time of the conflict.
The article went on to show the universality of the theme light vs. darkness, as it traverses both Christian and Islamic cultures.
Happy Yalda, and the real Christmas!