sura 7, verse 54:  "(God) covers the day with the night which is in haste to  follow it..." 
sura 36, verse 37:   "And a sign for them (human beings) is the night.  We strip  it of the day and they are in darkness." 
sura 31, verse 29:  "Hast thou not seen how God merges the night into the day  and merges the day into the night." sura 39, verse 5:   "...He coils the night upon the day and He coils the day  upon the night."

 The first verse cited requires no comment. The second simply  provides an image. It is mainly the third and fourth verses quoted above that provide interesting material on the process of interpenetration and especially of winding the night upon the day and the day upon the night. (sura 39, verse 5) 'To coil' or 'to wind' seems, as in the French translation by R. Blachere, to be the best way of translating the Arabic verb kawwara. The original meaning of the verb is to 'coil' a turban around the head; the notion of coiling is preserved in all the other senses of the word. What actually happens however in space? American astronauts have seen and photographed what happens from their spaceships, especially at a great distance from Earth, e.g. from the Moon. They saw how the Sun permanently lights up (except in the case of an eclipse) the half of the Earth's surface that is facing it, while the other half of the globe is in darkness. The Earth turns on its own axis and the lighting remains the same, so that an area in the form of a half-sphere makes one revolution around the Earth in twenty-four hours while the other half-sphere, that has remained in darkness, makes the same revolution in the same time. This perpetual rotation of night and day is quite clearly described in the Qur'an. It is easy for the human understanding to grasp this notion nowadays because we have the idea of the Sun's (relative) immobility and the Earth's rotation. This process of perpetual coiling, including the interpenetration of one sector by another is expressed in the Qur'an just as if the concept of the Earth's roundness had already been conceived at the time-which was obviously not the case. Further to the above reflections on the sequence of day and night, one must also mention, with a quotation of some verses from the Qur'an, the idea that there is more than one Orient and one Occident. This is of purely descriptive interest because these phenomena rely on the most commonplace observations. The idea is mentioned here with the aim of reproducing as faithfully as possible all that the Qur'an has to say on this subject. 

  The following are examples: 

• In sura 70 verse 40, the expression 'Lord of Orients and Occidents'. 
• In sura 55, verse 17, the expression 'Lord of the two Orients and the two Occidents'. 
• In sura 43, verse 38, a reference to the 'distance between the two Orients', an image intended to express the immense size of the distance separating the two points.