Everything is a Witness to the Power of Allah

Allah tells us about the signs He created that are indicative of His complete power and great might. He made the rays that come forth from the bright sun as the source of light, and made the beams that come forth from the moon as light. He made them of two different natures so they would not be confused with one another. Allah made the dominion of the sun in the daytime and the moon in the night. He ordained phases for the moon, where it starts small then its light increases until it completes a full moon. Then it begins to decrease until it returns to its first phase at the conclusion of the month. Allah said:

وَالْقَمَرَ قَدَّرْنَـهُ مَنَازِلَ حَتَّى عَادَ كَالعُرجُونِ الْقَدِيمِ - لاَ الشَّمْسُ يَنبَغِى لَهَآ أَن تدْرِكَ القَمَرَ وَلاَ الَّيْلُ سَابِقُ النَّهَارِ وَكُلٌّ فِى فَلَكٍ يَسْبَحُونَ

Similarly, it was said in the second verse (6) that there are signs in the coming of the night after the day and the day after the night, and in everything Allah has created in the heavens and the earth. These are open proofs (of the Oneness of Allah and the inevitability of the Hereafter) for those who fear Allah.

That they are proofs of the Oneness of Allah (Tauhid) is not difficult to see. He has the power to make things happen. He makes things as no one can. He creates everything without the help of materials, personnel and prototype, and has the mastery to operate them under a system that never breaks or must be replaced.