Astronomy and Pythagorean Mathematics? This is at best A VERY SPECULATIVE IDEA: The Star of David, a six-sided star or hexagram is known among Hebrews today as Mogen David. It was also called Solomon’s Seal and consisted of two interlaced triangles.
The Star of David is appropriately called a “STAR” and – in our “very speculative” view – it represents a double-triangulation which “maps” the position of the major stars of the heavens with the major axis along the Milky Way from Sirius to Aquila. As such, the Star of David was originally the secret symbol of the stargazing priests, later adopted by the Israelite Kings David and Solomon and subsequently by the Hebrew people as a whole.
Well, it could be that it had something to do with astronomy. I had the above idea many years ago, but have really not found probative evidence to support it, so it must remain rather pure speculation for now.