You can also read and listen to this episode on our blog: https://islamic-audio-book.com/10-the-structural-differences-between-the-sun-the-moon-and-the-stars/
The Sun is the only source of light in the Solar System, and the Moon merely reflects the light reaching it from the Sun.
The word "light" in Arabic refers to the Moon, while the word "lamp" refers to the Sun. The word "star" comes from the Arabic root "najama," meaning "appearing, emerging, visible."
We now know that the Moon does not emit its own light, but reflects that reaching it from the Sun. The Sun and stars also emit their own light. 
These facts were revealed in the Qur’an in an age when mankind simply did not have the means to make scientific discoveries of their own accord. It was an age when peoples’ knowledge of celestial bodies was severely restricted, to say the least. This further emphasises the miraculous nature of the book of Islam.