Radak

Their line is gone out through all the earth: – Their line, i.e. (the line) of their construction; and so (in the verse) “line upon line” (Is. 28:10), because the structure is made by stretching out the line. He means that the work of the spheres and constellations has gone out into all the earth. And so And their speech to the end of the world: – See, their works are their words. In them hath He set a tabernacle for the sun: – For the sun He hath set a tabernacle and a place in the spheres. The enumeration refers to the sun because he is the great light and because there obtains to men from him a greater benefit than from the rest of the stars through his light and heat, to men and to the rest of living things and to the plants. And when he says in them, he means in one of them, as he was buried “in (one of) the cities of Gilead” (Judges 12:7); and this (location) is the fourth of the seven spheres in which are the seven planets. He says in them, because these stars are fixed in the body of the spheres. And so it says (Gen. 1:17): “And God set them in the firmament of the heaven” and it does not say upon the firmament. And so, too, in the words of our Rabbis of blessed memory (Midrash Tanhuma, 2 Gen. v.), “The stars are fixed in the firmament like the nails which are fixed in a door.”