*On the Day of the Full Moon in the month of May* “Vesak”, the Day of the Full Moon May 17 (A/RES/54/115)
Changes anually based on the Day of the Full Moon in the month of May
http://www.un.org/en/events/vesakday/
http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/54/115
