Every morning, the sun comes up. Sometimes it is hidden from our view by clouds. The sun is a symbol of Christ. He rose early in the morning. He is the light and life of the world. Without the sun, we would die. Without Christ, we would die.
Though our earthly night is dotted with light (which lights are mostly suns) the night still represents life without Christ (who is Light). The Telestial Kingdom, which is compared to the stars, is life without Christ.
Even though we are not totally devoid of light at night (with stars, moon, and artificial lights), those lights cannot hold a candle to the light the sun gives to us. Thus, even the lights at night are a witness that God is "greater than they all." (Not a genuine scripture quote.) In fact, the artificial lights bring to mind the scripture about walking in your own light and in the fire ye have kindled (my computer crashed a while ago, I'm not using my own computer, and the scriptures on lds.org are a pain to search through and a pain to use because of the addition of letters to the text, referring to footnotes, thus I am not looking up that scripture. It may be in Isaiah, though).
The rising of the sun bears witness of the resurrection. It bears witness that Christ is the Light and Life of the world.
All of nature bears record of our Savior and Lord. If we had eyes to see, and understanding of the generosity of the signs of God, we would know that - a real knowledge.