ELI5: Explain Like I'm 5

Movable Western Christian observances

Okay, imagine you have a calendar, like the one we use to keep track of the days and months. On this calendar, there are some special days that Christians celebrate. These special days are called observances or holidays, and they are all about important events in the life of Jesus and other important figures in Christianity.

Now, here's the thing: Some of these observances or holidays have a fixed date, which means they always happen on the same day every year. For example, Christmas is always on December 25th.

But then, there are some observances that don't have a fixed date. They don't always happen on the same day each year. They can move around in the calendar. These special observances are called movable observances.

One of the most famous movable observances is Easter. Easter is a very important Christian holiday that celebrates the resurrection of Jesus Christ from the dead. The date of Easter changes every year. It can fall in March or April, but it's never on the same date every year. Sometimes it's early, and sometimes it's late.

Now, you might be wondering, "Why does Easter move around like that?" Well, it has to do with how the date is determined. The date of Easter is based on a special calculation that was made a long time ago by Christian leaders. They decided that Easter should be celebrated on the first Sunday after the first full moon following the vernal equinox (the first day of spring).

Because the vernal equinox and full moons happen at different times each year, Easter ends up moving around. It can be confusing, but this way, Christians all around the world can celebrate Easter together, even if they are in different places.

But Easter is not the only movable observance. There are other important Christian days that can also move around. For example, Ash Wednesday, which marks the beginning of the season of Lent, can fall on different dates each year, depending on when Easter falls.

So, in summary, movable observances are special Christian holidays that don't have a fixed date and can move around in the calendar. They include important events like Easter and Ash Wednesday, and they move because they are based on certain calculations that help Christians all around the world celebrate together, no matter where they are.