Astronomy and astrology are these days not really on speaking terms, so to speak. Once this was different when astronomers were also astrologers. I read the book The 12th planet by Zecharia Sitchin about exactly this.
He gives an outline of the history of astronomy that fascinates me. It got me to reading about Sumerian clay tablets, Akkadian Seals. I studied Japanese language and culture, but I now wish I would have studied Arabic, Sumerian, Akkadian or any language from that area instead. Anyway, this is my way of dealing with this information here and now.
Sitchin also mentions that the solar system once had a 12th planet and that travelers from the stars arrived eons ago. They also supplied astronomers and others of that time with information about the universe, the planets and the stars. Sitchin gives a lot of evidence on this and I like to explore this further.
So, who is Mr. Sitchin? What did he do? What does he have to say about the origin of the solar system and the astronomical views in Sumer and Babylon?
Wikipedia publishes several pages on Zecharia Sitchin. Here is one that talks about the controversy of his theories. Russian born Zecharia Sitchin was raised in Israel. As a boy he was reprimanded for taking the stories of the Bible literally. It is from that time that he becomes fascinated with the Nephilim or the Gods that visited Earth from Heaven. As far fatched as it may seem, Zecharia began a life long quest to find evidence that indeed Gods visited Earth from another place somewhere in heaven. Together with a legion of scholars he studied the archaeological remains as well as Sumerian, Babylonian, Assyrian, Hittite, Canaanite and other ancient texts and epic tales. They increasingly confirmed the accuracy of the biblical references to kingdoms, cities, rulers, places, temples, trade routes, artifacts, tools and customs of antiquity. Sitchin began asking himself
“Is it not now time to accept the word of these same ancient records regarding the Nephilim as visitors to Earth from the Heavens? … All the ancient people believed in gods who descended to Earth from the heavens. The tales were not given credibility because scholars saw them as myths.
The Twelfth Planet, p. vii
Sitchin on Astronomy
Before checking on the Sumerian information that he found during his investigation he reviews the history of our knowledge of Earth and the heavens around it. Here is a short outline of what he writes, or at least I am trying to be brief here… 
Sitchin began writing about the seven members of the solar system that were in use for centuries. The planets being Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. Earth was not counted as a planet, because ‘it was believed that these other celestial bodies circle Earth – the most important celestial body created by God, with Gods most important creation, Man, on it.’ Reference is made of the several world views that were used earlier in history.
Different views Ancient astronomers
Most traditional astrology works with the concepts of Ptolemy who lived in the second century AD. He was convinced that the Sun, Moon, and five planets moved in circles around Earth. Other ideas from that time are that the earth is flat and vaulted over by the distant heavens. The planets were moving through the star covered heavens around planet Earth. This astronomy predominated for over 1300 years until Copernicus put the Sun in the center.
Nicholas Copernicus is credited with the discovery that the Earth is only one of several planets in the heliocentric, Sun centered, system. Copernicus pored over the writings of Greek astronomers who preceded Ptolemy, such as Hipparchus and Aristarchus of Samos. 2000 years before Copernicus ‘these Greek astronomers listed the planets in their correct order from the Sun, acknowledging that the Sun, not Earth, was the solar system’s focal point. The heliocentric concept was only rediscovered by Copernicus, and the interesting fact is that astronomers knew more in 500 B.C. than in A.D. 500 and 1500.'
Sitchin explains how the astronomers in 500 B.C. could be so well informed. His best suggestion is that they could draw on Mesopotamian sources. Hipparchus confirmed in his writings that his studies were based on knowledge accumulated and verified over many thousands of years. The most acknowledged source of Greek astronomical knowledge was Chaldean .
Sitchin mentions that the Old Testament also ‘was replete with astronomical information. Joseph compared himself and his two brothers to twelve celestial bodies, and the patriarch Jacob blessed his twelve descendants by associating them with the twelve constellations of the zodiac’. 
The scope of Mesopotamian astronomy on which the early Greek astronomers must have been vast. Sitchin is sure that many of the later texts were more astrological than astronomical in nature. The heavens and the movements of the planets appeared to be of much importance to kings, temple priests and the people of the land in general. ‘The purpose of the stargazing seemed to be to find in the heavens an answer to the course of affairs on earth: war, peace, abundance, famine.’
Babylonian and Hellenistic astrology
A certain R.C. Thompson compiled and analyzed hundreds of texts from the first millennium B.C. and he was able to show that the astrologers of the time were concerned with the fortunes of the land, its people and its ruler. To make the statements that they did, they needed comprehensive and accurate astronomical knowledge without which no omens were possible. They said things like: ‘When Jupiter goes with Venus, the prayers of the land will reach the heart of the gods’. Or ‘If the Sun stands in the station of the Moon, the king will be secure on the throne.’ The Babylonians and Assyrians kept accurate ephemeris, the tables listed and predicted the future positions of the celestial bodies. They were familiar with comets, meteors, and other celestial phenomena and could calculate the relationships between the movements of the Sun, Moon, Earth and predict eclipses. They followed the motions of the celestial bodies and related them to Earth’s orbit and rotation through the helical system, this is the system we still use today. So in the Hellenistic age they had knowledge of this, over 2000 years ago!
Professor George Sarton wrote ‘Chaldean Astronomy of the last three centuries B.C.’  and found that the future positions of the celestial bodies were computed by two methods. One used in Babylon and an older one from Uruk. The Uruk system was more sophisticated and more accurate than the latter system.
A specific Akkadian seal from around the third millennium B.C. is used by Sitchin to explain what symbols were used for certain celestial bodies. What does Sitchin have to say about this seal? This seal has the catalogue number VA 243 and is said to be in the Vorderasiatische Museum in Berlin. There is controversy over the meaning of this seal, opinions vary considerably.
According to Sitchin this seal ‘departs from the usual manner of depicting the celestial bodies. It doesn’t show them individually, but rather as a group of eleven globes encircling a large, rayed star. It is clearly a depiction of the solar system as it was known to the Sumerians: a system consisting of twelve celestial bodies’. The star is a symbol for the Sun and all the 11 orbs are indicating the planets. Many scholars have commented on the theory of Sitchin and as always people are either against or approve of it .
 This piece of text is based on the pages 178-203 of the 12th planet-book.
 In 1530, Copernicus completed and gave to the world his great work De Revolutionibus. He claimed that the earth rotated on its axis once daily and traveled around the sun once yearly: a fantastic concept for the times. It is to be noted that other ancient Greek astronomers, Aristarchus and Nicholas of Cusa, did have ideas similar to those more fully developed by Copernicus but they were rejected in favor of the geocentric or earth-centered scheme as was espoused by Aristotle. Picture and information taken from Eric Weisstein’s world of Scientific Biography.
 “Chaldean” was used by several ancient authors to denote the priests and other persons educated in the classical Babylonian literature, especially in traditions of astronomy and astrology. Quote from Encyclopedia Britannica online.
 Quote taken from the book The 12th planet, page 183. I have found this to be correct. The story of Joseph can be found in Genesis 37 where Joseph has two dreams. The 12 sons of Jacob can also be found in Genesis 49. Several articles on this are here and here.
 The book ‘Chaldean Astronomy of the last three centuries B.C.’ has not been found available. There is mention made of it in the Journal of the American Oriental Society, Vol. 75, No. 3 (Jul. – Sep., 1955), pp. 166-173. I did find a book called ‘Hellenistic Science and Culture in the Last Three Centuries b.c.’ by George Sarton, Dover Publications ISBN: 0486277402.
 ‘The twelfth planet’, page 204.
 More information on the seal can be found on these websites: http://www.ianlawton.com/mes6d.htm,