The phase of the moon affects a variety of phenomenon relevant to humans.  The time and level of high tide (and low tide), the intensity of nighttime illumination, and the time of moonrise (and moonset) are all but determined by the phase of the moon.  Moon phase also affects the orbits of communication satellites, animal behavior, and the trajectory of space vehicles.  Additionally, lunar calendars (calendars synchronized with the phases of the moon) are used in many parts of the world.