Finding the long weekend in spring

Around these parts, we get a long weekend in spring - Easter. But it's always changing. Last year it was in March. This year it's in mid-April. How is one supposed to know when it will occur in future years?

I knew the timing has something to do with the first full moon after the spring equinox. The Astronomical Society of South Australia web site has a page that explains how it's calculated, and it lists Easter Sundays from 1700 to 2299.

For example, in 1700, it was on April 11. In 1891, it was March 29. In 1981, it was April 19. In 2135, it will be on April 3.