As for the question that what is meant here by the NUMBER(7)? We think that the exact SEVEN in number is intended, and it can be proved from other verses. The undermentioned verse clearly indicates that all the planets, stars, asteroids, or whatever might be, are all stationed within the realm and bonds of the first sky; as follows:

      ``HE then formed the sky into seven firmaments (SKIES) in two days (PERIODS), and to each sky He assigned its duty, AND WE ADORNED THE LOWER SKY WITH BRILLIANT STARS AND SECURITY, that is the ordering of the All-mighty, the All-knowing.''

QURÄN - S 41: 12

      Therefore the lowest of the seven skies is that which we can see overhead, which contains all the stars planets, suns, moons, and all the heavenly bodies that one can see with his eyes or can't see.

      The upper six skies are now unknown to us, and we know not much about them. Perhaps in future, science and knowledge, may come to discover what do they have, and on what a nature they stand, revealing some of their secrets.