It seems like everything with our calendar is based around 24hr days and the number of 24hr days to revolve around the sun. But a 24hr day can be broken down to 1,440 minutes and in turn 86,400 seconds. How did we (humans) calibrate the second so that exactly 86,400 would be 1 rotation of the earth to the point where we never need something like a “leap second” like we have with leap years?
In: Planetary Science
Other have mentioned leap seconds, but the reason the second is so precise is because that’s how we defined it. There’s nothing special about the length of a second, and there could have as easily been 100,000 per day, or 50,000, or 86,129 if that’s what people wanted. Ancient timekeepers picked 24 for hours and 60 for minutes and seconds simply because they were easy numbers to work with, and how long they are was determined by dividing the natural length of a day (the time between the Sun reaching the highest point in the sky twice) evenly into those units. The length of a second defined by atomic motion is just sciencing up the number because 1/86400 of a day is not precise enough for certain applications.
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