Explained in detail · 12

فَقَضَىٰهُنَّ سَبۡعَ سَمَٰوَاتࣲ فِي يَوۡمَيۡنِ وَأَوۡحَىٰ فِي كُلِّ سَمَآءٍ أَمۡرَهَاۚ وَزَيَّنَّا ٱلسَّمَآءَ ٱلدُّنۡيَا بِمَصَٰبِيحَ وَحِفۡظࣰ اۚ ذَٰلِكَ تَقۡدِيرُ ٱلۡعَزِيزِ ٱلۡعَلِيمِ

So He completed them as seven firmaments in two Days, and He assigned to each heaven its duty and command. And We adorned the lower heaven with lights, and (provided it) with guard. Such is the Decree of (Him) the Exalted in Might, Full of Knowledge