Considering the questions that science still has regarding space and the galaxies, one cannot reach a definite conclusion on what is exactly meant by “the seven heavens”. Nevertheless, some viewpoints have been stated regarding this subject. But we mustn’t forget that the main goal of the Quran is the training and guidance of mankind and when the Quran mentions instances such as the seven heavens, the movement of the sun and earth etc., in addition to it being correct in what it is saying, it is actually pointing to the never-ending might of Allah (swt) and preparing the grounds for getting familiar with Allah (swt) and thinking about his creation. Also, some of the scientific facts mentioned in the Quran need time and experimental scientific proof. Therefore, if science doesn’t say anything regarding a Quranic theory, that doesn’t necessarily mean it is incorrect.
In order to find out what is meant by “the seven heavens”, a few points must first be mentioned:
2) The literal meaning of “Sama” (sky) is as follows: “Sama” comes from the root word “Sumoww”, which means elevation, some Arabic linguists even claim that anything that is located above something else is a “sky” in relation with the lower object and the latter is called an “earth” in relation with the higher object.
3) “Sama” in the Quran:
The word “sama” and its derivatives have been mentioned in the Quran 310 times in which have been used for two meanings:
a) A materialistic meaning:
The Quran has used this word (sama) for its materialistic meaning in many instances, such as:
1) Meaning upwards: اصلها ثابت و فرعها فی السماء “…whose root is firmly fixed, and its branches (reach) to the sky” 
2) Meaning the atmosphere surrounding the earth: “ و نزلنا من السماء ماءً مبارکاً” “And we send down from the sky blessed rain” 
3) Meaning space, the place where the stars and other planets are located: “Blessed is He who made constellations in the skies, and placed therein a lamp and a moon giving light” 
b) A spiritual meaning:
The holy Quran has also used the word "sama" in its spiritual meaning many times:
1) Meaning the level of “nearness” and “presence” in which this world’s affairs are originally managed from: “He directs the affairs from the sky to the earth”
4) What is meant by “sab’” (seven)?
The word sab’ is used in two ways in Arabic:
a) For the number seven, which is a digit used in mathematics.
b) To signify abundance and large sums and quantities.
5) What the Quran means by the term “Seven Skies”:
Interpreters of the Quran say that there are several possibilities concerning the meaning of this term:
a) Here, if seven means the digit seven, “seven skies” can be referring to one of two things:
1) Seven skies full of stars and galaxies like the sky of planet earth. In this case, there are chances that there are also seven worlds out there similar to ours that haven’t been discovered yet.
2) Seven levels of “nearness”, “presence”, and high spiritual things (the seven skies), in contrast to the seven low levels of materialistic being in nature (the seven earths).
b) If “seven” is being used here to show abundance and large sums, three meanings are possible for the abovementioned term (the seven skies):
1) That Allah created many skies (each sky being a collection of planets, galaxies, stars etc.) and many earths (planets made of soil similar to our planet) in which all are suspended in space.
2) That Allah has created the many different layers of the atmosphere and has also created the different layers of the earth or different parts of the earth.
3) That Allah has created different levels of spirituality, ranks of nearness and presence, and high spiritual objects as well.
Given the fact that we don’t have enough information on the meaning of “the seven skies” in the Quran, and that science still has many questions regarding space and different galaxies, one cannot reach a definite conclusion and all of the theories expressed merely theories that aren’t certain. Yet, one must remember that the Quran’s main goal is the spiritual guidance and growth of mankind. Therefore, when the Quran speaks of “the seven skies and earths”, the movement of the sun and earth etc., in addition to what it is claiming is absolutely true, it is pointing to the never-ending might and power of Allah. Also, when such subjects are mentioned by the Quran, it is easier for man to get more familiar with his lord and think about his vast and astonishing creation. Furthermore, some of the scientific material in the Quran needs more time and scientific evidence to be proven. Therefore, if science doesn’t say anything on a specific Quranic theory, that doesn’t necessarily mean it is incorrect.
For further information, see:
1) Dr. Mohammad Ali Rezai Esfehani, Pejoohesh dar E’jaze Elmiye Quran (A Research on the Scientific Miracles of the Holy Quran), v.1, pg. 134.
2) Mohammad Taqi Mesbah Yazdi, Ma’arefe Quran, pg. 234.
3) Makarem Shirazi, Tafsir Nemooneh, v.1, pg 165.
 Baqarah:29, Isra:44, Mu’minoon:86, Fussilat:12.
 Mulk:3, Nuh:15
 Talaq:12; الَّذِی خَلَقَ سَبْعَ سَماواتٍ وَ مِنَ الْأَرْضِ مِثْلَهُنَّ یَتَنَزَّلُ الْأَمْرُ بَیْنَهُنَّ “Allah is He who created seven heavens and of the earth the like of them, the decree continues to descend among them”
 Hasan Mustafawi, Al-Tahqiq fi Kalemat al-Quran al-Karim, (The ministry of guidance and culture, first printing,
 Ragheb Isfahani, Mufradat, Al-Maktabah al-Radhaviyyah Press,
 جعل فی السماء بروجاً و جعل فیها سراجاً و قمرا منیراً Furqan:61.
 یدبّر الامر من السماء الی الارض Sajdah:5
 See: Mohammad Taqi Mesbah Yazdi, Ma’arefe Quran (Dar Rahe Haqq Press,
 و فی السماء رزقکم و ما توعدون Dhariyat:22
 Al-Tahqiq fi Kalemat al-Quran, ibid, v.1, pg.165, Mufradat Ragheb, root word: Ardh (ارض)
 See: Allamah Tabatabai, Al-Mizan (Isra Press,
 See: Tantawi Jawhari, Tafsir al-Jawahir (Dar-ul-Fikr, Bita,) v.1, pg.46, Dr. Mohammad Ali Rezai Esfehani, Pejoohesh dar E’jaze Elmiye Quran, ibid, v.1, pg. 126-142.
 See the website of The Center of Quranic Teachings and Culture.