"They can never fathom the greatness of God. The whole earth is within His fist
on the Day of Resurrection. In fact, the universes are folded within His right
hand. Be He glorified; He is much too high above needing any partners."
The picture you have just seen shows a minute number of stars and nebulae in our own galaxy, the milky way. To bring the awesome dimensions of the universe into perspective, first try to imagine how much is a million! If you collect a handful of sand on the beach you will hold in your palm about a million grains of sand. Now have you ever imagined how many grains of sand there are on every beach on earth? Quite a large number?
Did you know that there are more stars in the universe than all the grains of sand on every beach on earth?
But that is not all, the Quran speaks of seven universes, layered as seven spheres one inside the other. Our universe is the inner most of the seven, and thus the smallest of the seven. All the heavenly bodies that we see in the sky (planets, asteroids, comets, stars, nebulae, galaxies, quasars .. etc) are part of our innermost universe (41:12, 55:33, 67:5, & 72:8-12).
It is not possible to comprehend God's Greatness, but by just trying to visualise the immensity of His creation, we get a modest indication of His greatness.
Light, which is the fastest mover in the universe, travels at a speed of 300,000 Km per second! For light to travel from one end of our galaxy across to the other end takes 100,000 years .... and this immense distance is only within our own galaxy! Our universe contains a billion or more other galaxies! Each of these galaxies contain billions of stars like our own sun!
If we attempt to simply count the stars in our own galaxy, which are estimated to be in excess of 100,000 million stars (100,000,000,000), and count one star per second it will take us 3170 years to count them. To count the stars in all the universe becomes unthinkable. But this is only how long it takes just to count them; but God created them! Such is the greatness of God.
If the diameter of our own galaxy (which is the innermost) is 100,000 light years, can you imagine the diameter of our own universe (the 7th)? .... Can you imagine the diameter of the universe that encircles us? What about the 4th and 3rd up to the 1st outermost universe? There becomes no words to even attempt to conceive of such magnitudes.
In 39:67 we are told that this incomprehensible vastness of the seven universes is "within the fist of God's hand." Can you imagine from the outer limit of the outermost universe, where is the planet Earth?
How significant is it? On the infinitesimal mote called Earth, such minuscule creatures as Mary, Jesus, and Muhammad lived. Yet, some people set up these powerless humans as god-like figures, and place their names alongside the name of Almighty God!
God's greatness is represented not only by the fact that He holds the seven universes in His hand, but also by the fact that He fully controls every atom, even subatomic components, everywhere in the greater universe (6:59, 10:61, & 34:3).
P.S. The expression of God holding the seven universes in His Hand, is an allegorical one. It represents God complete control and authority over all His creation.