Mystery #3Tier 2earth & space / time
Why do we bolt an extra day onto February every four years?
Most years February has 28 days, but every so often it grows a mysterious 29th. We call it a leap year, and it turns up like clockwork every four years. Nobody just fancied a spare day for fun. So what is that extra day quietly fixing?
Your guess
Why do you think we sometimes need to squeeze in an extra day?
There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.
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