In addition to using light bulbs for the stars in deep space, the cast also used a matte painting as a backdrop with small cracks to create the illusion of perspective on the moon.
Famous inventor and businessman Thomas Edison said, " Of the 200 light bulbs that didn't work, every failure told me something that I was able to incorporate into the next attempt."
Absolutely, and the one that is on actually already covered the light bulb up, so we know that light's not going to play a factor in the shark's behavior.