The Sumerian calendar

The Sumerian calendar

The Sumerians and Babylonians were probably the first people to use what we now recognise as a modern calendar. The basis of this was the lunar cycle and the Sumerian year was made up of 12 lunar cycles. But 12 moon cycles fall short in relation to the solar year. So not to fall out of sync with the seasons, the Sumerian astronomers introduced an extra month every four years. The high time for Sumerian astronomy and astrology was the 6th century B.C. and a group of scribes, among them  Enuma Anu Enlil were at the forefront. It is still unclear how these scribes were trained and where all this knowledge came from. But what is certain is that most of them worked later at the Babylonian court where they helped to shape the Babylonian calendar. Compared to the later famous Babylonian astronomy, these were indeed humble beginnings, but they laid the foundation of the houses, star signs and the zodiac. It was also the beginning of astrology, when aspects in the sky and movements of the planets were observed and recorded and then certain symbolic meaning  derived from repeat events.

During this period, the first day of each month (beginning at sunset) continued to be the day when a new crescent moon was first sighted—the calendar never used a specified number of days in any month and finishes again with the last sighting of the Waning Moon. Then follows 2 days of New Moon period when no moon is visible.

Subsequently the Sumerian calendar was not only absorbed into the Babylonian calendar, but a lot of other cultures such as the Ancient Greeks, Egyptians and Hebrews also absorbed elements into their own calendar system. In particular the Sumerian calendar was used as a blueprint of many religious calendars who are still in use today.

From the 5th century B.C. the Sumerian calendar slowly transformed into a luni-solar calendar, meaning that both the solar and the lunar cycles played an important part and were brought into alignment. This principle was later formally described by the Greek astronomer Methon of Athens around 430 B.C. He concluded that 19 solar years equal exactly 235 lunar months and this discovery that underpins the luni-solar calendar is now called the Metonic cycle.

The Living With the Moon lifestyle calendar is also based on the Ancient Lunisolar Calendar, now believed much older than the Babylonian Calendar. Some sources put its existance back to the Minoan civilisation (2700-1450 B.C).

The cow jumped over the moon

The cow jumped over the moon

Most of you know probably know the nursery rhyme Hey Diddle Diddle
The cat and the fiddle,
The cow jumped over the moon.
The little dog laughed,
To see such sport,
And the dish ran away with the spoon.

I always pondered particularly at the line ‘ The cow jumped over the moon’, thinking it was just silly little nursery rhyme to pacify children who would not want to go to sleep. But in fact, there there is a theory that ‘the cow jumped over the moon’ related to the Ancient Goddess Hathor and was probably badly translated from Ancient Greek texts and put into a nursery rhyme.

I recently visited Knossos, the birthplace of the Minoan civilization. For all of you that have not heard much about this place, Knossos was the largest Minoan royal palace, situated in Crete.

The Minoans were the first major culture in Europe ( 2700 to 1450 B.C.) to worship only one God. They left behind palaces, advanced pieces of pottery, fantastic jewelry and many unsolved mysteries. Below you can see the throne room where ‘King Minos’ reigned in the palace that is famous for its Minotaur.

  • The Minoan had a lunisolar calendar
  • They were the first monotheist society and their god was a woman – similar to later Demeter – the Mother Earth

I undertook a tour at the famous ruins and towards the end of the tour I asked where was the famous labyrinth and the guide answered – you are standing in it – it was the palace itself. It had so many rooms that foreign visitors saw it as a labyrinth. My remaining question of course was – and where was the Minotaur?

According to legend, Minos prayed to Poseidon to send him a snow-white bull as a sign of support and as offering to the Goddess. But Minos did not slaughter the bull but kept it instead alive. So Poseidon punished him by making Minos’ wife Pasiphae fall in love with the bull and conceive an offspring called the Minotaur, half man – half bull.

The bull was always very connected to the Minoan culture. There are still frescos preserved which show young athletes, male and female, jump over a bull. But why would a bull jump over the moon?

Babylonian calendar records exist that points to a very possible Minoan connection and suggest that the existence of the lunisolar calendar and solar and lunar phenomena were recorded more than a thousand years before the Babylonians and came from the Minoans in Crete.

A rich and seafaring civilization such as the Minoans would have had a calendar system of sorts and would have traded with Egypt, the Phoenicians and Sumerians. Furthermore, King Minos was not one person, but a title, such as Ceasar or Pharoah. So there were many King Minos and their time in office was limited to one big lunisolar cycle, lasting around 8 years. Then a new King Minos would come into office. The most likely explanation is the octagonal cycle that occurs every 8 years when Venus completes her cycle and returns in its original position at the same point in the sky. As no firm calendar records survive we can only speculate.

But it would totally correspond with the practices of other cultures, including the Mayans. They also used the Venus cycle (when the path of Venus, the Earth and the sun align) together with the lunar phases to calculate the synodic period of Venus (584 days). The ratio of the earth cycle to Venus is 8:5. So 5 Venus years and 8 Earth years coincide, making this a marker when the sky resets to its original position. This is quite significant in a time when there were no other ways of recording precise timings.


So coming back to the cow and the moon. The Minotaur most likely represented the worship of the sun and the moon. The mother goddess = nature, represented by the 8-year cycle where the Sun, the Earth and Venus perfectly aligned again – and the Moon God (represented by a bull with 2 horns showing the Waxing and the Waning Moon and the moon cycle). The monster Minotaur was most probably a ritual involving bulls and sacrifices in the palace of Knossos. This was followed by sporting events, a sort of blueprint of the later Olympic Games.

But why is the cow jumping over the moon and not the other way round? The bull-jumping has certainly something to do with it. We know that the Minoans build their palaces to align with the solstices and the winter solstice seems to have had a particular significance, as it symbolized the rebirth of the sun.

The star Orion, ‘the bull of the sky’, is visible in the Northern Hemisphere between November and February and rises over the crescent of the winter moons. Could that be the cow jumping over the moon?