Pascha is the Orthodox Easter, the feast of the resurrection of Christ and the greatest festival of the Eastern churches, the "feast of feasts". It keeps the same paschal rule as the West, the first Sunday after the first full moon on or after the spring equinox, but computes it on the older Julian tables, with the equinox reckoned by the Julian calendar and the moon by the traditional Alexandrian cycle. Because the Julian calendar now runs thirteen days behind the Gregorian, and the lunar tables differ, Orthodox Pascha usually falls one, four or five weeks after Western Easter, and only sometimes on the same day.
A further rule, honoured in practice, keeps Pascha after the Jewish Passover, following the Gospel sequence. Proposals to agree a common date, discussed most notably at Aleppo in 1997, have not been adopted. The occasional coincidences (as in 2025) are periodic accidents of the two calendars, not a settlement. The divergence is a live ecumenical question and, for the many Orthodox living among Western Christians, an annual and visible one.