Yalda Celebration, watering the tree of hope and joy in the longest night of the year
Yalda Festival, Jashn-e Shab-e Yalda, is an Iranian festival celebrated on the longest night of the year that is, in the night of the Northern Hemisphere's winter solstice. Calendrically, this corresponds to the night of December 20/21 (±1) in the Gregorian calendar, and to the night between the last day of the ninth month, Azar, and the first day of the tenth month, Dey, of the Iranian calendar.