Astronomy and The Calendar

Astronomy in Ancient Mesopotamia was as much a mixture of religion and astrology as it was a science, but its methods had a significant influence on later Western astronomers.The Ancient Mesopotamians helped lay the foundation for all of modern Western astronomy.


 

Ancient Babylonian astronomers.
Ancient Babylonian astronomers.

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who were the first astronomers?

The Sumerians were among the first astronomers, mapping the stars into sets of constellations, many of which survived in the zodiac and were also recognized by the ancient Greeks. They were also aware of the five planets that are visible to the naked eye. Without the aid of telescopes, Sumerian astronomers followed the movements of the stars, and identified the planets Mercury, Venus, Mars, Jupiter and Saturn.


In the 6th century B.C. the scribes of Enuma Anu Enlil were a group of men at the Babylonian court who were experts in astronomy and astrology. Texts refer to this group of scribes, but we do not know exactly who they were, what they did and how they were trained. However, for hundreds of years the scribes kept accurate records of natural events on the earth and in the sky in order to predict the future.

Sumerian astronomy was primitive compared to later Babylonian standards. Babylonian clay tablets that have survived since the dawn of civilization in the Mesopotamian region – record the earliest total solar eclipse seen in Ugarit on May 3, 1375 BC.

Source: http://www.crystalinks.com/sumercalendars.html

Which were the  babylonian astronomical Innovations ?

Venus Tablet Of Ammisaduqa, 7th Century.
Venus Tablet Of Ammisaduqa, 7th Century.

image source: http://fineartamerica.com/featured/2-venus-tablet-of-ammisaduqa-7th-century-science-source.html

The Babylonians were the first civilization known to possess a functional theory of the planets. The oldest surviving planetary astronomical text is the Babylonian Venus tablet of Ammisaduqa, a 7th-century BC copy of a list of observations of the motions of the planet Venus that probably dates as early as the second millennium BC. The Babylonian astrologers also laid the foundations of what would eventually become Western astrology. The Enuma anu enlil, written during the Neo-Assyrian period in the 7th century BC, comprises a list of omens and their relationships with various celestial phenomena including the motions of the planets.

The Babylonians not only recognized Venus as the same object whether itappeared in the morning or evening, but they actually developed a method for calculating the length of the Venus cycle. According to the Babylonians, the length of one cycle was 587 days, compared with the actual value of 584 days. The slight difference is due to the fact that they attempted to coincide these astronomical cycles with phases of the moon.

In Babylonian cosmology, the Earth and the heavens were depicted as a “spatial whole, even one of round shape” with references to “the circumference of heaven and earth” and “the totality of heaven and earth”. Their worldview was not exactly geocentric either. The idea of geocentrism, where the center of the Earth is the exact center of the universe, did not yet exist in Babylonian cosmology, but was established later by the Greek philosopher Aristotle’s On the Heavens. In contrast, Babylonian cosmology suggested that the cosmos revolved around circularly with the heavens and the earth being equal and joined as a whole. The Babylonians and their predecessors, the Sumerians, also believed in a plurality of heavens and earths. This idea dates back to Sumerian incantations of the 2nd millennium BC, which refers to there being seven heavens and seven earths, linked possibly chronologically to the creation by seven generations of Gods.

However, besides being the manifestation of legends, the constellations provided a practical use for the people of ancient Mesopotamia. Like in other societies, the orientation of the constellations was used to mark seasons for harvesting or sowing crops. Certain constellations were noted for their yearly rising or setting times, and provided an accurate clock by which time could be measured. The Babylonians kept written records of calendars used for planting.

In the 12th century BCE, Babylonian astronomers began to compile “star catalogs”lists of the visible stars, grouped into constellations. Many had Sumerian names, demonstrating the continued influence of Sumerian astronomy in Babylon. Some of the constellations identified by the Babylonians – including Taurus, Leo, Scorpio, Capricorn, Gemini and Cancer – are still recognized by astronomers and astrologers today.

One of the major breakthroughs of the Babylonians was their invention of the degree system to distinguish positions in the sky. The system was similar to our use of degrees to calculate latitude and longitude. The Greeks adopted the degree system and also many of the Babylonian constellations, which they renamed in Greek.

Source: https://en.wikipedia.org/wiki/Babylonian_astronomy

Full Reconstruction of the Babylonian Star-Map.
Full Reconstruction of the Babylonian Star-Map.

image source: https://solariapublications.com/2011/10/25/map-2-full-reconstruction-of-the-babylonian-star-map/

who were the Chaldeans?

In the later Babylonian Empire, the individuals responsible for studying the skies were known as Chaldeans. Although these priest-astronomers continued to use the old star catalogs to predict celestial phenomena, they also developed mathematical models that allowed them to anticipate astronomical events without consulting the records. This ability to “foretell the future” must have seemed magical to the general population, and the Chaldeans enjoyed positions of great power and respect within the social and religious hierarchy.

Probably the most famous Chaldean was Seleucus of Seleucia, who lived around 200 BCE. Unlike most of his contemporaries, Seleucus believed that the Earth and the other planets revolved around the Sun, as did Copernicus 1700 years later. Seleucus was also the first to suggest that the Earth’s tides are caused by the action of the Moon, and that the height of the tides depends on the Moon’s position relative to the Sun.

Source: http://www.brighthub.com/science/space/articles/123842.aspx

tide
Explanation of tides.

image source: http://sarosh30.blogspot.it/2016/04/understanding-tides.html

the evolution of the calendar

The Sumerians were the first to divide a circle into 360 parts, providing a system of measurement for angles. We still use this system today. They invented these forms of measurement in order to study the movements of the stars and planets. Using their knowledge of astronomy, the Sumerians developed the twelve-month calendar based on the cycles of the moon. It was probably invented in order to keep track of religious festivals. They also kept track of days of labor in order to pay workmen.

The lunar calendar was synchronized with the solar year (the seasons) by intercalation of a leap month every few years. The Sumerians of Babylon were probably the first people to make a calendar. They used the phases of the moon, counting 12 lunar months as a year. To make up for the difference between this year and the year of the seasons, they inserted an extra month in the calendar about every four years. The early Egyptians, Greeks, and Semitic peoples copied this calendar. Later the Egyptians worked out a calendar that corresponded almost exactly to the seasons.

In ancient Sumer there were two “seasons” in the Sumerian year a “summer” season Emesh which began on the Vernal Equinox – and a “winter” season, Enten, which began on the Autumnal Equinox. New Year’s day was an important holiday (when the sacred marriage rite was performed).This was celebrated around the Vernal Equinox, depending on the synchronization of the lunar and solar calendars.The new year and month would begin on the first New Moon, after the completion of the old lunar year. The day began and ended at sunset and contained twelve hours.

It is important to note the similarity of the old Sumerian calendar and the Hebrew calendar, including the timing of the Hebrew Passover (around the same time as the Sumerian New Year), and the beginning of the Hebrew Sabbath (at sundown).

Source: http://www.crystalinks.com/sumercalendars.html

Assyrian Calendar - Ashur 1800BC.
Assyrian Calendar – Ashur 1800BC.

image source: https://it.pinterest.com/pin/357473289142902214/

The early Romans also used a calendar based on the moon. The year in this calendar was 355 days long. The months corresponding to March, May, July, and October each had 31 days; February had 28 days; and the rest had 29. An extra month was added about every fourth year. The high priest regulated the calendar. On the calends, or day of the new moon, he announced to the people the times of the nones (first quarter) and ides (full moon) for that month. The word calendar is from the Latin word kalendae. The priests, however, performed their calendar-keeping duties poorly, and by Julius Caesar’s time they had summer months coming in the spring. Caesar corrected this situation in 46 in the Julian calendar. He adopted the plan of the Egyptian astronomer Sosigenes’s 365-day year, with one day added every fourth, or leap year. He distributed the extra ten days among the 29-day months, making them identical with the months today. Julius Caesar’s correction of one day in four years – 1/4 day, or six hours, a year – made the calendar year longer than the year of the seasons. Thus anniversaries began coming earlier and earlier in the year. In 1582 the vernal equinox, or beginning of spring, occurred on March 11 instead of the correct date, March 21.

Pope Gregory XIII remedied this by directing that ten days be dropped from the calendar and that the day after Oct. 4, 1582, should be October 15. He also directed that three times in every 400 years the leap-year arrangement should be omitted. The new calendar was called the Gregorian, or New Style (N.S.), calendar. It was adopted by Roman Catholic countries, but Protestant and Eastern Orthodox countries long continued to use the Old Style (O.S.), or Julian, calendar. The new calendar was not adopted in England until 1752, when it was necessary to drop 11 days. The Eastern Orthodox church accepted the New Style in 1923, when 13 days were “lost.” The Chinese had adopted it in 1912. Another reform that the Gregorian calendar affected was general adoption of January 1 as the beginning of the year. Until then some nations began it with December 25, others with January 1 or March 25 – as England did before 1752.

Source: http://www.crystalinks.com/sumercalendars.html

Pope Gregory XIII.
Pope Gregory XIII.

image source: http://study.com/academy/lesson/pope-gregory-xiii-accomplishments-legacy.html

info sources: http://www.crystalinks.com/sumercalendars.html

http://www.thelivingmoon.com/43ancients/01documents/Mesopotamian_Astronomy.html

http://www.brighthub.com/science/space/articles/123842.aspx

https://explorable.com/mesopotamian-astronomy

https://en.wikipedia.org/wiki/Babylonian_astronomy

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