In the time of Josephus, the Sun was in the constellation Aries at the time of the Vernal Equinox, the first day of Spring in the northern hemisphere. And so in the traditional Jewish observance, the Passover feast begins with the Full Moon during the month of the Equinox.

What's in a Name?

The early church celebrated Passover in a similar manner to Jewish observances, though the customs changed over time. But our Christian Easter observance is still based on the Hebrew Passover observance. For example, many churches observe the solemn, penitent "Holy Week" observance before Easter, based on the seven-day Feast of Unleavened Bread.

Many people today argue that "Easter" is really a pagan holiday, with bunnies and eggs symbolizing heathen fertility rites, not the resurrection of Jesus.  Entire books have been written to show that the name "Easter" is derived from the name of the Babylonian fertility goddess "Ishtar" or "Astarte." Eggs and bunnies are clearly not of Biblical origin. But the name issue is mostly a matter of the semantics of the English language since other European languages paint a different picture.

The Hebrew word for "Passover" is "pesach." In Greek, the translated word is "pascha." Throughout church history, this name has been associated with the feast of Christ's resurrection. This name of this feast is translated in the following ways in the languages of the traditionally Christian nations of Europe:

Spanish   = Pascua
Italian   = Pasqua
French    = Paque
Russian   = Pascha
Swedish   = Pask
Norwegian = Paske
Dutch     = Pasen

However, in the English language, the feast of Christ's resurrection is commonly called "Easter." For example, in Acts 12:4 in the King James Bible, the word "Easter" is given as a translation of the word "pascha." If you read old-fashioned English writings, it's not uncommon to see the Easter feast called "The Pasch" (pronounced "pask") and Jesus often figuratively referred to as "the paschal lamb" and so forth. However, the word "Pasch" is out of style in our shallow generation of English speakers.

It appears that the word "Easter" is derived from the name of an old Anglo-Saxon fertility goddess associated with the east who had a springtime festival. The German word is "Ostern," and since the Anglo-Saxons were originally a Germanic tribe, it's pretty clear that the words are related. While old habits apparently die hard in the English and German languages, it's pretty clear that most traditionally Christian nations name the Pasch as the proper name of the feast of Christ's resurrection. 

The Reckoning of the Pasch

In the early days of the church, Christians kept the Pasch in the same manner as the Jews, beginning on the 14th of Nisan. But as time went by, Christianity developed distinctive observances that differed from Jewish practices. 

In the church at Rome, it became customary to celebrate the Pasch on the Sunday following 14 Nisan, in order to commemorate Jesus' rising on the first day of the week. This became a controversy in the late Second Century. Victor I, the bishop of Rome, argued that the churches of Asia Minor should follow the Roman practice, rather than celebrate the Passover on 14 Nisan in the Jewish manner. 

Since the early centuries, the Christian churches used the official Julian civil calendar of Rome to calculate the date of the Pasch. Since it was not always easy to know the date of the Equinox, calendar tables were prepared years in advance. The Roman method of calculating is explained here by the English scholar, the Venerable Bede, who wrote a definitive work on the subject around 700 A.D.: "The beginning of this month ought to be observed according to this rule, so that the 14th Moon of Easter never precedes the vernal equinox, but correctly appears either on the equinox itself (that is March 21) or after it has passed."