NavList:

Alex Eremenko, you wrote:
"When you say "average" you have to specify over what is this average taken. Over the day of the Easter Sunday after tomorrow (lunar distance certainly changes during the day), or over all Easter Sundays from the very first one until the present time ?"

Yes, indeed. I left that open intentionally to make the puzzle more puzzling (?). Also there are different ways of defining Easter. This year eastern and western Easter both fall on April 16. They have done so every three years or so in the 21st century so far but skipped a whole decade before that and will go eight years without a match after this year. But if you want a specific, what is the average true lunar distance of the Moon from the Sun (and is it always waning?) at noon GMT on Easter as defined by western churches for the 20th and 21st centuries (or some subset at least a decade in length)?

Speaking of averages, here's a good trick question for fans of things astronomical and celestial: what is the average distance of the Earth from the Sun? Or to make the question, more extreme: what is the average distance of Halley's comet from the Sun? Most astronomy texts are quite casual with the concept of "average distance".

Frank Reed