Answer: If there was no sun, the water cycle would not be able to occur. The sun provides the energy that drives the water cycle, through the process of evaporation. Without the sun's energy, water on Earth would not be able to evaporate from the surface, and the cycle would not be able to begin. Additionally, the sun is responsible for driving the winds, which are responsible for the movement of water vapor in the atmosphere, so without the sun, the winds would stop too. As a result, precipitation and runoff would not occur, and the water in the oceans, rivers, lakes, and underground would not move. Without the sun, the water cycle would come to a complete stop, and the water on Earth would be static.