article_snippet.sent: Unlike Christmas, it doesn't fall on the same day every year but shifts around in spring depending upon cosmic events.
article_snippet.sent: And that blood moon we just had -- is it pure coincidence that it fell around Easter?
article_snippet.sent: Which brings us to the question of how astronomy is used to determine the date of Easter Sunday.
article_snippet.sent: A blood moon appeared in the sky early Saturday, right between Good Friday and Easter Sunday and during Passover.
article_snippet.sent: Many Jewish holidays, including Passover, fall on full moon, which is also a prerequisite for a lunar eclipse, the event that turns A blood moon a blood red color.
article_snippet.sent: a rule would fall on the first Sunday after the first full moon following the vernal equinox.
article_snippet.sent: That's the day in March when Earth's axis reaches a midpoint between winter and summer and the day and night are of equal length.
article_snippet.sent: But ... if the first full moon following the vernal equinox fell on Sunday, Easter would be pushed down a week.
article_snippet.sent: In 1997, the World Council of Churches pushed for a unified method of determining a date based on astronomical occurrences.
highlights_snippet.sent: Why is the date different every year, and what does it have to do with the moon?