Why 60 Seconds, 60 Minutes But 24 Hours?


Wed, Jul 27th, 2011 20:00 by capnasty NEWS

Scientific American looks as to why a minute has 60 seconds, an hour 60 minutes, but a day only has 24 hours.

From the article:

Thanks to the ancient civilizations that defined and preserved the divisions of time, modern society still conceives of a day of 24 hours, an hour of 60 minutes and a minute of 60 seconds. Advances in the science of timekeeping, however, have changed how these units are defined. Seconds were once derived by dividing astronomical events into smaller parts, with the International System of Units (SI) at one time defining the second as a fraction of the mean solar day and later relating it to the tropical year. This changed in 1967, when the second was redefined as the duration of 9,192,631,770 energy transitions of the cesium atom. This recharacterization ushered in the era of atomic timekeeping and Coordinated Universal Time (UTC).



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