Tides depend on both the moon and sun. So does the phase of the moon. Tides are largest at full moon and new moon, when their gravity gradients combine to enha

Tides depend on both the moon and sun. So does the phase of the moon. Tides are largest at full moon and new moon, when their gravity gradients combine to enhance each other's tides. A week later, their gravity gradients interfere, decreasing the amplitudes of the tides.