 Yaldā Night

Shab-e Yalda ("Yalda night" ) or Shab-e Chelleh ("night of forty", ) is an Iranian festival celebrated on the "longest and darkest night of the year", Yalda is a winter solstice celebration, 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 ("D"ey) of the Iranian civil calendar.