The Ethiopian calendar (; "yä'Ityoṗṗya zëmän aḳoṭaṭär") is the principal calendar used in Ethiopia and also serves as the liturgical year for Christians in Ethiopia and Eritrea belonging to the Orthodox Tewahedo Churches (Ethiopian Orthodox Tewahedo Church and Eritrean Orthodox Tewahedo Church), Eastern Catholic Churches (Eritrean Catholic Church and Ethiopian Catholic Church), and Eastern Protestant Christian P'ent'ay (Ethiopian-Eritrean Evangelical) Churches (most Protestants in the diaspora have the option of choosing the Ethiopian calendar or the Gregorian calendar for religious holidays, with this option being used when the corresponding eastern celebration is not a public holiday in the western world). The Ethiopian calendar is a solar calendar that has more in common with the Coptic calendar of the Coptic Orthodox Church of Alexandria and Coptic Catholic Church, but like the Julian calendar, it adds a leap day every four years without exception, and begins the year on August 29 or August 30 in the Julian calendar. A gap of seven to eight years between the Ethiopian and Gregorian calendars results from an alternative calculation in determining the date of the Annunciation.