Knowing how to use a lens is essential in learning photography. Your digital SLR camera has a unique capability to allow you to change lenses depending on your needs so undertanding when, how and what lens to use is an important aspect of photography.
This charts show the effect of aperture on the size of the starbursts. As you can see, the smaller the aperture, the more emphasized the starburst. The same concepts apply during the daytime as they do during the night time.