The Sumerian Flood Trilogy

Ur Time: The Secrets of the Calendar and Clock

The special date and time that greet you on our website are designed to act like a time machine, transporting you thousands of years into the past—to the heart of Mesopotamia, to the glorious city of Ur in the age of the Sumerians. Our display is a carefully crafted modern reconstruction inspired by the timekeeping systems believed to have been used during the reign of King Ur-Nammu (circa 2112 BCE), at the end of the 3rd millennium BCE. So how does this ancient calendar and clock work? Let’s discover it together:

 

The Calendar System: A Rhythm in Harmony with Nature (Mu, Month, Day)

The Dance of the Moon and Sun:
The Sumerian calendar was neither purely lunar nor purely solar; it was a delicate lunisolar system that harmonized the cycles of both the Moon and the Sun. This allowed the calendar to track lunar phases while also staying aligned with the seasons.

The Moons of Ur:
Months were defined by the Moon’s cycle in the sky and traditionally began with the first sighting of the new crescent Moon. In our model, these beginnings are approximated using modern astronomical data (UTC new moon times). The month names displayed are authentic names from the Ur III period, the golden age of the city of Ur.

The Beginning of Time (Mu):
To create a historical framework, we’ve designated the reign of King Ur-Nammu, founder of the Third Dynasty of Ur (circa 2112 BCE), as the starting point of our calendar—“Mu 1” (Year 1). The "Mu" number you see reflects the number of Sumerian years that have passed since that time.

The Aligning Adjustment (Dir):
To prevent the lunar calendar from drifting out of sync with the solar year, the Sumerians employed a clever solution: every few years, they added a 13th “intercalary” month! This extra month, called “Dir,” kept the calendar in perfect harmony with the seasons and nature. Our model follows this periodic insertion principle as well.

 

Time Measurement

The Hour Born from Sunset (Danna, UŠ)

Beginning of the Day:
Unlike today, a Sumerian day began at sunset. Therefore, our time calculations take the moment of local sunset in ancient Ur as the start of each new day.

Divisions of the Day (Danna):
A full day (from one sunset to the next) was divided into 12 equal parts. These segments, called “Danna,” each represent roughly 2 modern hours.

The Pulse of the Moment (UŠ):
To measure time more precisely, each Danna was subdivided into 30 equal parts. These units, called “UŠ,” represent brief moments of about 4 modern minutes each.

Instant Display:
The expression "X. Danna Y. UŠ" on the screen shows how much time has passed since the last sunset in Ur—that is, which major (Danna) and minor (UŠ) time units of the day we are currently in.

 

A Bridge to the Modern World

To help relate this ancient system to the present day, we also display the corresponding modern Gregorian date and the current time for the Ur/Mesopotamia region (UTC+3) in parentheses alongside the Sumerian time.