http://www.sitchiniswrong.com/VA243seal.pdf
Analysis of Sitchin's claim that Sumerians knew of a 10th planet.
Highlights:
1. The inscription on the seal (left hand and right hand sides – which are not discussed by Sitchin) says nothing about planets or any element of astronomy.
2. The alleged “sun” symbol on the seal is not the sun. We know this because it does not conform to the consistent depiction of the sun in hundreds of other cylinder seals and examples of Sumero-Mesopotamian artwork.
3. If the “sun” is not the sun, then what are the dots? The dots are also stars, as is best illustrated by the Sumerian-Mesopotamian depiction of the Pleaides (seven dots together with reasonable astronomical accuracy since they are visible to the naked eye)
4. There is not a single text in the entire corpus of Sumerian or Mesopotamian tablets in the world that tells us the Sumerians (or later inhabitants of Mesopotamia) knew there were more than five planets. This is quite a claim, but is demonstrable through the work of scholars who specialize in cuneiform astronomy. Below I list all the major works on cuneiform astronomy (catalogues of texts, dissertations / books) and invite readers to check them out of a library and look for themselves. Literally every cuneiform text that has any astronomical comment (even with respect to astrology and omens) has been translated, catalogued, indexed, and discussed in the available academic literature. The tablets are often quite detailed, even discussing mathematical calculations of the appearance of planetary bodies in the sky, on the horizon, and in relation to other stars. The field is by no means new, and is considerably developed.
So the full (rather boring) inscription of VA243 reads: “Dubsiga, Ili-illat, your/his servant.” Nothing in the inscription suggests anything remotely to do with astronomy or planets.
etc etc etc