These graphics explain why Easter Sunday changes each year based on ancient interpretations of the solar and lunar cycles.

Easter is a moveable feast - it can happen anytime between March 22 and April 25. It is set using a mathematical calculation of the lunar and solar cycles.

So, why does Easter fall on a different date every year ... As early as the year 222, Romans were using different methods to calculate the dates of Easter. Some methods relied on the 19 ...