He is the One Who has made the sun (a source of) light and (with that) made the moon shine, and appointed for it stages (to appear smaller or bigger) so that you might compute the number of years and the count (of time). Allah has not created (all this) but with a zero-defect strategy. (Through these cosmic realities) He expounds in detail the Signs (of His Creativity, Unicity and Might) for those who possess knowledge.

 Surah Yunus- 05

  Imam Razi (May Allah shower His Mercy on him) writes in Tafseer Kabeer and Imam Ismail Haqqi (May Allah shower His Mercy on him) writes in Tafseer Ruh Al Bayan that the sun is the fountainhead of radiance and the moon takes it light from the sun.  For this reason, Allah Ta'ala uses the word "Zia" for sun, which is used for inherent (own) light and for moon, the word "Noor" is used, which is for light taken from another source.
 

 It is given in Tafseer Kabir:

 Translation: That the moon is behind the sun means that moon takes it light from the sun.

 (Tafseer Kabir, Surah Shams-02)

 It is given in Tafseer Ruh Al Bayan:

   Translation: Do you not see that the light of the moon is taken from the sun and the light of the sun is its own?