The ecclesiastical rules are: Easter falls on the first Sunday following the first ecclesiastical full moon that occurs on or after March 21 (the day of the ecclesiastical vernal equinox). This particular ecclesiastical full moon is the 14th day of a tabular lunation (new moon).
That's a very pagan way of setting a celebration date -- which can be any Sunday from March 22 to April 25 inclusive. And the ecclesiastical full moon is not the same as the real full moon. It might not be random but it sure seems that way: plus or minus two and a half weeks.
Why not just celebrate it on the real Vernal Equinox?
The Resurrection celebration is tied intimately to Passover which is tied to the Luna cycle. It would be considered Pagan only if there were actual worship of alternative gods.
(Western Roman) Easter is always celebrated on a Sunday.