Snuffy, Orthodox Pascha (Greek for Passover) and Western Easter only coincide when the Paschal full moon—the first full moon following the vernal equinox—is later than April 3 on our modern (Gregorian) calendar. That's because Julian Calendar dates are currently thirteen days later than their corresponding Gregorian dates. Thus, April 3, Gregorian, equates to March 21, on the Julian Calendar. It's possible for Orthodox Pascha to follow Western Easter by as much as five weeks. Beginning in the year 2100, the Paschal full moon must be later than April 4 for the two observances to coincide. In a couple of thousand years, when the gap between the two calendars exceeds a full lunar cycle, Orthodx Pascha and Western Easter will never coincide; at least for a hundred thousand years or so.

      - Mark