The verse 11 of Sura Tarik in the Qur'an, refers to the "returning" function of the sky.

"By Heaven with its cyclical systems." (The Qur'an, 86:11)

This word interpreted as "cyclical" in Qur'an translations also has meanings of "sending back" or "returning".

As known, the atmosphere surrounding the Earth consists of many layers. Each layer serves an important purpose for the benefit of life. Research has revealed that these layers have the function of turning the materials or rays they are exposed to back into space or back down to the Earth. Now let us examine with a few examples of this "recycling" function of the layers encircling the Earth.

The troposphere, 13 to 15 kilometers above the Earth, enables water vapor rising from the surface of the Earth to be condensed and turn back as rain.

The ozone layer, at an altitude of 25 kilometers, reflects harmful radiation and ultraviolet light coming from space and turns both back into space.

The ionosphere, reflects radio waves broadcast from the Earth back down to different parts of the world, just like a passive communications satellite, and thus makes wireless communication, radio, and television broadcasting possible over long distances.

The magnetosphere layer turns the harmful radioactive particles emitted by the Sun and other stars back into space before they reach the Earth.

The fact that this property of the atmosphere's layers, that was onlt demonstrated in the recent past was announced centuries ago in the Qur'an, once again demonstrates that the Qur'an is the word of God.