A person would have to have an understanding of the fundamentals of linguistics to really appreciate the answer to this question; however, I hope you'll gain a renewed appreciation, as well.

Where did the Greeks obtain the myth of "Zeus"?
Explain the history of "Zeus".

We typically pronounce "Zeus" as Zoos; however, in Greek, Ζευς is pronounced Zay-us. If you listen closely, you can hear its similarity to the word Deus, which is understood as the Latin name for God (as in Deus ex machina). The idea of Zeus simply arises from the universal understanding of the creative process; the Greeks put their own spin on it. There are many similarly spelled names in the mythologies of many cultures. Here are some examples:

1) Indo-European: Dyeus
2) Roman: Jupiter, which is a corruption of Deus Pater, God the Father.
3) Vedic: Dyaus Pitr
4) Slavic: Div
5) Germanic: Ziu

Is "Zeus" an astronomical personification?

Superficially, the answer is yes. However, I'm not wholly satisfied with the explanation of the origin of the word "Zeus" or "Deus". While I agree that the the word "day", with its attendant attribute, "shining", are cognate with "Dei", as represented by the sun, there is a deeper meaning that linguists tend to overlook. It has to do with the universal creation myth: first, there is the One, all that is, and from the One comes (the) Two (Diu), the many gods who oversee the different aspects of daily life. This explains the similarity between the word "Deus" and deuce (meaning two). This creation story originated well before the monotheistic model of religion.

Symbolically, the idea of one would be the non-physical point, as the closest representation of the Monad: the totality of being. Next, the idea of two would be the "Tau" cross (Tau as two, again), as the closest representation of the Dyad: duality or otherness. The Tau cross is represented alternately as either two intersecting lines (like the small letter "t") or a vertical line topped by a horizontal line (like the capital letter "T"), representing emergence in the process of creation. Both symbols are accurately named "tau" for the Greek letter, as the first one is an earlier symbol; however, the second symbol is more commonly associated with the idea. Now, where do think the Asian "Tao" came from?

While I'm drawing on internet sources to illustrate my points, most of my understanding comes from a lifelong fascination with linguistics. I also took three semesters of ancient Greek toward a Greek minor, to supplement my philosophy degree. Consequently, I've striven very hard to articulate the intertwining ideas discussed here. I hope I've been successful in conveying how truly fascinating and pervasive the universal creation story is in our thinking.

Respectfully,
Shin