Moon Viewing Ceremonies (called Tsukimi in Japan) are held each year in autumn to celebrate the full moon and waxing moon in Japan.
This symbol shows Japanese pampas grass and dango (sweet dessert food) which are used in the ceremony, as well as the moon in the background.
Moon Viewing Ceremony was approved as part of Unicode 6.0 in 2010 and added to Emoji 1.0 in 2015.
U+1F391
? Moon viewing ceremony