The Moon is Earth's only natural satellite. It orbits Earth at an average distance of 384399 km (238,854 mi; about 30 times Earth's diameter). The Moon's orbital period (lunar month) and rotation period (lunar day) are synchronized by Earth's gravitational pull at 29.5 Earth days, making the same side of the Moon always face Earth. The Moon's pull on Earth is the main driver of Earth's tides.