At a time when it was held that the Earth was the center of the world and that the Sun moved in relation to it, how could anyone have failed to refer to the Sun's movement when talking of the sequence of night and day? This is not however referred to in the Quran and the subject is dealt with as follows:

Sura 7, verse 54:

Sura 36, verse 37:

Sura 31, verse 29:

Sura 39, verse 5:

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 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 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 dayis quite clearly described in the Quran. 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 Quran just as if the concept of the Earth's roundness had already been conceived at the time - which was obviously not the case.

This view is sometimes contested by examples from great thinkers of antiquity who indisputably predicted certain data that modern science has verified. They could hardly have relied on scientific deduction however; their method of procedure was more one of philosophical reasoning. Thus the case of the Pythagoreans is often advanced. In the Sixth century B.C., they defended the theory of the rotation of the Earth on its own axis and the movement of the planets around the sun. This theory was to be confirmed by modern science. By comparing it to the case of the Pythagoreans, it is easy to put forward the hypothesis of Mohammed as being a brilliant thinker, who was supposed to have imagined all on his own what modern science was to discover centuries later. In so doing however, people quite simply forget to mention the other aspect of what these geniuses of philosophical reasoning produced, i.e. the colossal blunders that litter their work. It must be remembered for example, that the Pythagoreans also defended the theory whereby the Sun was fixed in space; they made it the center of the world and only conceived of a celestial order that was centered on it. It is quite common in the works of the great philosophers of antiquity to find a mixture of valid and invalid ideas about the Universe. The brilliance of these human works comes from the advanced ideas they contain, but they should not make us overlook the mistaken concepts which have also been left to us. From a strictly scientific point of view, this is what distinguished them from the Quran. In the latter, many subjects are referred to that have a bearing on modern knowledge without one of them containing a statement that contradicts what has been established by present-day science.