No text, but a visual code

[Koen G]

Knowledge of astronomy was pretty hit-and-miss at the time. The sun was considered to be the third "planet" orbiting the Earth after Mercury and Venus.

Right, though I guess there are two kinds of hit-and-miss. One is the knowledge we find incorrect now, but was correct in the medieval tradition. To include Sun and Moon in their respective places among the planets would have been the most informed decision at the time. A scribe or artist who did this had either copied his model correctly or knew his sources well.

But there is also hit-and-miss of the kind we see here. It was known that the ecliptic did not run from pole to pole like some meridian dividing the celestial sphere in half. So something went wrong here interpreting the text or copying the model