why does ukraine celebrate christmas on january 7th

Christmas is celebrated on January 7th in Ukraine due to a historical difference in the way the Julian calendar and the Gregorian calendar were adopted. When the Gregorian calendar was introduced in the 16th century, many Orthodox countries, including Ukraine, continued to follow the Julian calendar for religious and cultural reasons. As a result, Christmas in Ukraine is celebrated 13 days later than in countries that follow the Gregorian calendar.