I figure since this is the section for things that have no appropriate forum, and I see no section for Mesopotamian metrology or astronomy, I'll post it here.
Feel free to move if needed
So, right to the point
The modern Jewish calendar { Derived by Hillel II from Babylonian ephemeris } and the Civil calendar have a very interesting relationship
This is to the Saros cycle { The Same Saros seen in the Greek Antikythera mechanism }
A Saros { Greek } is from the Babylonian " Saru " { 3600 } and is the time t takes for the Sun, Earth and Moon to return to the same relative positions in a straight line
Our regular civil clock has 86,400 seconds to the day
The Jewish clock { for calendar purposes } uses 25,920 parts to the day
These are known as " chelekim " { Plural of chelek } and based on the Babylonian measure of the Barleycorn { the " she " }
Now, eclipse periodicity is notoriously hard to calculate, yet the Babylonians were able to calculate it { and other cycles } to a fraction of a second
The length of the Saros is approximately 223 synodic months (approximately 6585.3211 days, or 18 years, 11 days, 8 hours
Note: It's not an integer number of days
You need 1 / 3rd of a day to correctly predict the Saros { 8 hours }
The ratio between the units for a day in the Jewish and World Civil clock is
25,920 / 86,400 = .3
Feel free to move if needed
So, right to the point
The modern Jewish calendar { Derived by Hillel II from Babylonian ephemeris } and the Civil calendar have a very interesting relationship
This is to the Saros cycle { The Same Saros seen in the Greek Antikythera mechanism }
A Saros { Greek } is from the Babylonian " Saru " { 3600 } and is the time t takes for the Sun, Earth and Moon to return to the same relative positions in a straight line
Our regular civil clock has 86,400 seconds to the day
The Jewish clock { for calendar purposes } uses 25,920 parts to the day
These are known as " chelekim " { Plural of chelek } and based on the Babylonian measure of the Barleycorn { the " she " }
Now, eclipse periodicity is notoriously hard to calculate, yet the Babylonians were able to calculate it { and other cycles } to a fraction of a second
The length of the Saros is approximately 223 synodic months (approximately 6585.3211 days, or 18 years, 11 days, 8 hours
Note: It's not an integer number of days
You need 1 / 3rd of a day to correctly predict the Saros { 8 hours }
The ratio between the units for a day in the Jewish and World Civil clock is
25,920 / 86,400 = .3