Sunday, October 14, 2018

Why 60 Minutes?



-  2123  - Why 60 Minutes?  When clocks first came out they were divided with hours in halves, thirds and quarters but never minutes.  At the time it was just not practical to keep track of such small durations of time.  It was not until the 16th Century the minutes first showed up on clocks.
Somehow the longitude and latitudes on the Earth became measured in 360 degrees and 24 hour clocks. 
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----------------------------------  2123  -   Why 60 Minutes?
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-  We have 10 fingers and 10 toes so it is pretty easy to figure out how we ended up with the decimal system.  But, how did we end up with a hexadecimal numbering system for time and angles?  Why not have everything in one system? 
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-  Same reason the U.S. is on the English system and not the metric system like the rest of the world.  60 is a convenient number.  It is the smallest number divisible by 1,2,3,4,5,6 and also 10,12,15,20,30, but it would be more convenient if it were 100 rather than 60.
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-  Somehow the longitude and latitudes on the Earth became measured in 360 degrees and 24 hour clocks.  It all started over 4,000 years ago with a numbering system invented by the Babylonians.  And, have you noticed,  people just don’t like change.
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-  A Greek astronomer  ( 276 - 194 B.C.) used a hexadecimal system to divide a circle into 60 parts.  He needed these to divide up the Earth for a system of latitudes.  The horizontal, latitudinal  lines were simply running through well-known places on Earth at the time. 
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-  A hundred years later, Hipparchus (Note 1) normalized the lines of latitude making them parallel to Earth’s geometry.  Then, he devised the longitude lines that ran north to south over 360 degrees.  This was documented in Claudius Ptolemy’s book “Almagest” 150 A.D.( Note 2).
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-  Hipparchus went further and subdivided the 360 degrees into 60 parts called Partes Minutae Primae and then into 60 yet smaller parts called Partes Minutae Secundae.  The first division became minutes and the next division seconds.
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-  When clocks first came out they were divided with hours in halves, thirds and quarters but never minutes.  At the time it was just not practical to keep track of such small durations of time.  It was not until the 16th Century the minutes first showed up on clocks.
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-  We have kept the Hipparchus system ever since.  People just don't like change.  A day has 24 hours, each hour 60 minutes and each minute 60 seconds.
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-   Getting seconds from the rotation of the Earth became too awkward.  In 1967 the second was redefined as the duration of 9,192,631,770 energy transitions of a cesium atom.  That is the cesium clock used in atomic timekeeping and as the Coordinated Universal Time.

-  Then in order to keep atomic clocks in step with astronomical time they invented leap seconds.  So there are about eight times per decade that a minute gets 61 seconds, an extra leap second.  So, blame the Babylonians for 60 minutes and 60 seconds, but don’t blame them for Daylight Savings.  Blame your congressman for that.
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(1)  Hipparchus was the greatest Greek astronomer 190 -120 B.C. who invented many of the naked eye observation instruments that were used for 1,700 years before the telescope.  He measured the size and distance of the Sun and the Moon.  He used trigonometry to make these measurements and is considered the founder of trig.
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-  Using parallax he found the distance to the moon to be 30 times the diameter of the Earth         ( Earth’s diameter = 7,926 miles.  30*7,926 = 237,780.  Today we say 238,855 miles.  He was 99.5% accurate.) 
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-  He recorded the exact positions of over 1000 of the brightest stars using latitude and longitude.  He accounted for the recession of the North Pole, one cycle takes 26,700 years.  He defined the brightness magnitude of stars.  The same system is still used today with the star Vega being the standard brightness.
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(2)  Claudius Ptolemaeus (100-170) put the Earth at the center of the Universe.  He had the Sun, Moon and the 5 planets orbiting the Earth.  He worked out a system of epicycles and eccentrics to predict the positions of the planets.  It was used for 1,400 years until Tycho Brahe (1546-1601) came up with a more accurate system putting the Sun at the center.  He authored the book, "Almagest".
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-  October 14, 2018.       This Review was 747
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