Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, thank you very much for having confidence in us, and we hope our efforts, which are purely for Allah’s Sake, meet your expectations.
First of all, we would like to stress that Allah Almighty is the Sole Creator of the universe including the heavens and the earth.
Along the course of centuries, man has pondered over the universe and tried to discover its hidden secrets. Many concepts about the cosmos developed but they were subject to change later on.
Responding to your question, Dr. Muzammil H. Siddiqi, former President of the Islamic Society of North America and Director of the Islamic Society of Orange County, Garden Grove, California, states the following:
Seven skies are mentioned in the Qur’an in many places. It is interesting that the word “saba` samawat” also occurs seven times in the Qur’an. (See Al-Baqarah 2:29; Al-Israa’ 17:44; Al-Mu’minun 23:86; Fussilat 41:12; At-Talaq 65:12; Al-Mulk 67:3; Nuh 71:15) Only Allah knows the real nature of these seven skies. Maulana Mawdudi in his tafseer (explanation) of the Qur’an says, “It is difficult to explain precisely what is meant by the ‘seven heavens.’
In all ages, man has tried, with the help of observation and speculation to conceptualize the ‘heavens’, i.e., that which lies beyond and above the earth. As we know, the concepts that have thus developed have constantly changed. Hence, it would be improper to tie the meaning of these words of the Qur’an to any one of these numerous concepts.
What might be broadly inferred from this statement is that either Allah has divided the universe beyond earth into seven distinct spheres, or that this earth is located in that part of the universe which consists of seven different spheres.”
(Towards Understanding the Qur’an, translated by Zafar Ishaq Ansari, vol. 1, p. 58, note no. 34.)
From the Hadith (especially the hadiths concerning Al-Mi`raj) we learn that the first heaven is the one that is closest to the earth. So the order begins from the earth and the highest heaven is the seventh heaven.
Allah Almighty knows best.
Excerpted, with slight modification from, pakistanlink.net