Pascha (Greek: Πάσχα) (we prefer it to “Easter”), is the feast of the Resurrection of the Lord. Pascha is a transliteration of the Greek word, which is itself a transliteration of the Aramaic pascha, from the Hebrew pesach meaning Passover.
Pascha normally falls either one or five weeks later than the feast as observed by Christians who follow the Gregorian calendar. Occasionally the two observances coincide. The reason for the difference is that, though the two calendars use the same formula developed in Nicaea, in 325, to determine Pascha (the first Sunday following the full moon following the Spring equinox) the starting point is different. The older Julian calendar's solar calendar is presently 13 days behind the Gregorian's and its lunar calendar is four to five days behind the Gregorian's. The Pascha date this year is April 8. Next year, it will be April 28 and, in 2020, April 19. For 40 days following Pascha (the number of days between the Resurrection of Christ and His ascension), we greet one another with the words: Χριστὸς Ἀνέστη! Christ is Risen! And, we answer by saying Ἀληθῶς Ἀνέστη!, Truly, He is Risen!