The Julian calendar took effect under the reign of Julius Caesar in 45BC.
In 1582, Pope Gregory XIII created a new calendar to correct the discrepancy between calendar time and calculated astronomical time. But to begin with only Catholic countries adopted the changes and Orthodox Christian countries remained on the Julian calendar.
Over time, those countries adopted the Gregorian calendar for secular use but the Orthodox churches continued to base their liturgical calendar on the Julian timetable.
In 1923 a revised version of the Julian calendar was introduced bringing Christmas Day in line with the Gregorian calendar, but it was only adopted by some of the Orthodox Christian countries including Greece, Cyprus and Romania.
"When we open the church calendar on January 7, we're actually looking at the date December 25," Father Alexander Morozow of the Russian Orthodox Church in Canberra said.
"So we still have that same date, we're just using a calendar that hasn't caught up.
Lamb and , which is a type of Easter bread, are popular Easter dishes in many Greek Orthodox communities in the United Kingdom.
Easter lunches or festive meals are popular activities on Easter Day.The Orthodox Christian date for Easter Sunday, also known as Pascha, is often at a later date than the Easter date observed by many western churches.Many Orthodox Christians in the United Kingdom celebrate Holy Pascha according to the Easter date in the Julian calendar.On Sunday, it was discovered that Jesus' tomb was empty and angels informed onlookers that Jesus had risen.Throughout the next 40 days, Jesus appears to his apostles and disciples before finally ascending to heaven.For these reasons, Orthodox Easter is celebrated on the first Sunday, after the first full moon, following the vernal equinox and always after Jewish Passover.Many Orthodox Christians in the United Kingdom celebrate Jesus’ resurrection on Easter Sunday.Many churches hold night liturgies which occur at midnight between Holy Saturday and Holy Pascha (or Easter Sunday).These liturgies may last until the early hours of the Easter Sunday morning.That is because many Orthodox Christian churches follow the Julian calendar for religious celebrations.The Julian calendar runs 13 days behind the Gregorian calendar, the standard international calendar in use today.