Sumerian Advanced Astronomical Knowledge That Still Remains A Mystery For Historians

The Sumerians fascination with the heavens is apparent in the large number of seals and cuneiform tablets unearthed of an astronomical nature. Naturally, these astronomical discoveries came as a major surprise to the scientific world, the advancement shown here is truly head and shoulders above anything seen 6000 years ago. Indeed, some of these discoveries would not be rediscovered for centuries.There were many oddities found in the cylinder seals, especially (VA/243),which shows a 'star' with eleven planets surrounding it. However, as of now there are no known records of the of any 11th planet. What does the cylinder seal represent? Could it be they knew something that we don't? One of the biggest questions surrounding these findings is..where did the Sumerians get this knowledge from?