et - et hashamayim ve'et ha'aretz - the heaven and the earth
Whenever the word et appears it adds something to the meaning of the plain text.
The two words et here are meant to convey that two additional matters or raw materials were involved in the creation of heaven and earth. According to the plain meaning we understand the two words as references to the two different raw-materials (elements) G-d employed when creating heaven and earth, seeing the two are obviously not made of the same material. This is the meaning of "the earth was tohu vavohu" i.e., that after the initial act of creation earth was still in a chaotic state. The specific meaning of the two words is that the material tohu was covered with a form bohu.
This is what is meant by Yeshayahu 66:2. The first three words in that verse refer to existing material, whereas the last words "my hands have fashioned," refer to G-d supplying this material with distinctive form (tzurah). According to this verse in Yeshayahu, G-d first created the raw material, bara, but subsequently His activities consisted only of refining such raw material by acts of yetzirah respectively beriah, (creation of matter), consisted of merely creating the smallest physical particle, a nekudah (a point) something barely perceptible. This little particle formed the beginning of the entire solar system.
The number of planets is 955 corresponding to numerical value of the word hashamayim (the Hebrew final letter mem is considered as equivalent to 600). Our Sages say that at the time G-d descends from the celestial regions, i.e. from 955 heavens, and He seats Himself on the throne commensurate with His glory, all these heavens as well as the gateways recite the verse, "lift up your gates your heads..." (Tehillim 24:9)
In Derech Eretz Rabbah we find that, "G-d is the solitary Ruler in the celestial regions, His Name is One, and he resides in the 390 heavens" (the numerical equivalent of the word shamayim). Each one of these heavens has been stamped with His Name, a Name which has been alluded to in the Torah (Devarim 32:1) "ha'azinu hashamayim - hearken the Heavens."
Drash: The extra words et in the phrase "heaven and earth" include the sun, moon, stars in the word shamyim and the entire range of vegetation in the word eretz.
According to Kabbalah, there are only seven heavens as enumerated in Chagigah 12.