The gravitational pull of the moon controls the rise and fall of tides on Earth and slows the planet's rotation, while the phases of the moon serve as calendar markers for human beings. High tides occur on the portion of the Earth closest to the moon and the portion farthest away. Low tides occur between those two points.
The moon's pull slows the Earth's rotation in what astronomers describe as tidal braking. This effect adds 2.3 milliseconds to the length of a full day each century. As it collects energy from the Earth, the moon moves further away from the planet at a distance of 3.8 centimeters per year.
The lunar calendar is based on the time that elapses between full moons. For centuries, many civilizations acknowledged that the moon's cycles influence everything from the female menstrual cycle to planting and harvesting times for crops.
Over the years, many have claimed that there is a correlation between full moons and erratic or aggressive human behavior. However, studies on the subject have found no connection between the two.
As human beings transitioned from rural, agriculture-based lifestyles to more urban lifestyles, they have, as a group, grown increasingly unaware of the cycles of the moon.