Dear brothers, Allah the Almighty says: 

(Who has made the earth a resting place for you, and the sky as a canopy, and sent down water (rain) from the sky and brought forth therewith fruits as a provision for you. Then do not set up rivals unto Allah (in worship) while you know (that He Alone has the right to be worshipped).)

[Al-Baqarah, 22] 

Allah the Almighty has made the sky as a canopy, creating the gravity system between the planets. Had it not been for the closed orbits of the planets, the whole universe would have turned into one mass. 

In fact, the bigger object pulls the smaller one,

and as for the planets they rotate in a way that creates a centrifugal force that is equal to the gravitational one,

and the sky, as a structure, embraces all these forces. Had it not been for the closed orbits of the planets, their rotation in the sky would have been disturbing. Allah the Almighty describes the sky as follows: 

(By the sky (having rain clouds) which gives rain, again and again.) 

[At-Tariq, 11]

Gravitational and centrifugal forces: 

Every planet rotates in a closed orbit, and each rotation suits in its space and speed the gravitational force of another planet or star, causing by that the movement balance. In fact, everything in the sky, which is a huge structure, moves in a balanced way. 

I would like to make this point clearer by giving you an example in physics. If we have two identical magnates on a flat table, and we put a small steel ball in between, you need a lot of effort to keep this ball balanced in the middle, by making the pulling force of the magnates the same.

If you get the ball one tenth millimeter closer to the first magnate, it will be pulled by it, and if you get the ball one tenth millimeter closer to the second magnate, it will be pulled by it. Thus, the ball needs huge efforts to be balanced in between the two identical magnates.  

If the two magnates are of different sizes, let us say one of them is two thirds bigger than the other magnate, accurate calculations will be needed to keep the steel ball in a distance that suits the major gravitational force and the minor one. 

If we have three or four magnates which have different sizes and gravitational forces, things will be harder. Let alone, they are not put on a flat surface!  What if these objects- with their various sizes- are rotating in a space and they have different spaces and they mover in different speeds?

The inimitability is manifested in having many objects of different sizes, speedw and spaces rotating in a balanced way in the space; the balance in their rotation is exactly the inimitability that should be highlighted in this concern. Allah the Almighty says:     

(…and the heavens will be rolled up in His Right Hand.)

[Az-Zumar, 67]

In Allah's Hand is the dominion of the heavens and the earth, and this is the meaning of the Ayah in which Allah, Exalted and Sublime be He, says: 

(Who has made the earth a resting place for you, and the sky as a canopy…)

[Al-Baqarah, 22] 

Galaxies in the universe:

Allah the Almighty has made the sky as a canopy, structuring the system and the galaxies in it. One of you may ask, "How many galaxies are there in the universe?" The answer is, nobody knows, because the secrets of the universe are still unrevealed. However, due to the latest humble discoveries of the scientists, there have been billion galaxies discovered, and in one of these galaxies, there are one billion planets and stars. 

Galaxies are connected to one another by gravitational force, and they rotate in closed orbits. This is how the wondrous structure of the sky is designed on the basis of movement balance. Allah the Almighty says: 

(And We have made the heaven a roof, safe and well guarded.)

[Al-Anbiya', 32]

How could anyone disobey Allah? How can anyone do without His Mercy? How can anyone ignore His Torment? How can anyone turn away from Him? How can anyone doubt Allah's Promise and Menace? He is Allah in Whose Hand is the dominion of all things and the One Who has descended the Quran on the Prophet, peace be upon him. 

The Quran is His words, so when you read the Words of the Creator of this Universe, the Words of the One in Whose Hand is the dominion of all things, the Words of the One to Whom all affairs return, the Words of the One to Whom belong the keys of the heavens and the earth, the Words of the One Who cannot be questioned as to what He does, while they will be questioned, the Words of the One to Whom is the final return, he will be certain of this religion and its authenticity, in addition of having sound faith.