Why does earth spin on its axis, scientific explanation

We all know about rotation and revolution. Rotation causes day and night whereas revolution causes climate change. All the things in the universe rotates in their axis. We may not know the actual reason behind why do earth rotates. The revolution occurs due to the centripetal force tangent to the surface of the object. It revolves around the axis in the fixed path and by this simple moment climate change occurs.
       The main science behind the rotation of the earth is all our solar system has been formed by the masses of the clouds and if we observe it by sitting on the belt of our galaxy then we can see that whole of this particles and elements bombards with each other and due to this the earth spins on its axis. On the other hand some of the researchers also states that earth and all other planets are the product of the bigbang that occurs before billions of years ago. After bigbang all the planets began to spin very faster according to the theory of angular momentum conservation and conservation of energy. In simple definition they states that after bigbang they continue to move due to law of inertia. At the very beginning of the formation of earth it used to rotate very fast but slowly and gradually the gravity of the moon has dropped it down to the present spin level. The moon trues to stop the earth from moving but as it is very far from the earth it cannot do so. Unlikely it can surely will drop the spin level after billions of year.
   All the particles and molecules in the universe has different velocities and they move in different directions so the average velocities between them will become different. As a result they give rise to the angular momentum. The gravity between the particles will make the particles to condense and become contracted. When the particles are contracted there spin becomes faster. We can simply take an example of an ice skater whose spin will be double and treble when their arms are contracted towards they body but when their hands are out stretched then the spin will be slow. This moment of balancing of the spin is known as gyroscopic stabilization. Since the concept of the universe expansion appears to be real we can easily guess the slow spinning of the planets due to the contraction of galaxy obviously.
    This is the scientific explanation for the rotation or spinning of the earth around its axis.