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History of Time: Difference between revisions

→‎Calendars: adding to Greeks
(→‎Calendars: adding to Greeks)
 
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== Calendars ==
== Calendars ==
* meaurement of time based upon social need by measuring heavenly bodies
* measurement of time based upon social need by measuring heavenly bodies
=== Paleolithic calendars===
=== Paleolithic calendars===
*** 13,000 BC cave painting depicting cycles of the moon
*** 13,000 BC cave painting depicting cycles of the moon
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** based on star Sirius (they recognized some planets)
** based on star Sirius (they recognized some planets)
** 1st of the year = day of the Nile flooding
** 1st of the year = day of the Nile flooding
** 360 days x 12 months x 10 days @
** 360 days x 12 months x @ 10 days
** 12 month solar year  
** 12 month solar year  
** adopted by the Romans, used by Copernicus
** adopted by the Romans, used by Copernicus
=== Greek Calendar===
=== Greek Calendar===
** Hipparchus:  
* Hipparchus:  
** Greek astronomy: planets and motions... mathematics...
** applied Greek astronomy (sun, moon, stars, planets and their motions) and mathematics
*** Hipparchus’ definition of the procession of the equinoxes 2/3rd century b.c.
*** earlier Greek astronomers and mathematicians, such as Eudoxus of Cnidus, established these concepts
*** earth not an exact sphere
*** that the solar year was 365.24 days was already understood by them
*** he noted the discrepancy 1 degree / hundred years
*** Hipparchus measured the year more exactly to 365.24667 days or 365 days, 5 hours, 55 minutes, 12 seconds
** he also identified the "procession of the equinoxes"
*** = he understood that earth is not an exact sphere
*** and that the earth changes its rotation angle slightly, estimating it at 1 degree change per century
*** thus he identified the difference between:
**** "solar" or "tropical" year = the time for the earth to rotate around the sun as measured by equinoxes or solstices (i.e. in relation to the sun)
**** "sidereal" year = the time for the earth to rotate around the sun as measured against the stars, which is impacted by the "procession of the equinoxes"
 
=== Roman calendar ===
=== Roman calendar ===
* 10 lunar months: from Spring moon in March to late December... 300 days
* 10 lunar months: from Spring moon in March to late December... 300 days
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** but this system caused confusion
** but this system caused confusion
** so it was adjusted by Julius Caesar, Caesar Augustus, and others to bring regularity
** so it was adjusted by Julius Caesar, Caesar Augustus, and others to bring regularity
*** Augustus added months name for him and Julius Caesar thus using the calendar as official
*** February was shortened to 28 days, with an additional day added every 4 years (29 days)
**** the 29th day was called "Bissectus"
*** Caesar Augustus added month names for Julius Caesar (July) and himself (August) thus using the calendar for propaganda and authority


=== Gregorian calendar ===
=== Gregorian calendar ===
* 1582
* 1582


== Clocks ==
== Clocks ==