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Q&A: Leap Day Explained

29 Feb 2016, 07:01 UTC
Q&A: Leap Day Explained
(200 words excerpt, click title or image to see full post)

Question: I hear next Monday will be Leap Day. Why do we do that? And please keep your answer simple, because I’m not really that good at math. Thanks. — RO, Greenwich, England.
Answer: OK, I’ll try to keep it as simple as possible, but you might want to take a look this post from January. You can stop reading after the third paragraph and avoid the math. If the math doesn’t bother you, read the whole post. Then come back here for the simpler explanation. But it will help to see my animation first.
Unfortunately, I really can’t explain this without using math. We only need arithmetic — no geometry or trigonometry or calculus, I promise. First, here’s the purely non-mathematical answer to your question, as demonstrated in the animation: We need to have leap days because the true astronomical year is slightly longer than the (365 day) calendar year. If we ignored that fact, the error would accumulate. Eventually, your calendar would be telling you it’s Spring and time to plant. But outside, Mother Nature would be telling you it’s still Winter.
So what I wrote on my “virtual chalkboard” at top is a summary of the numbers ...

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