 The gravitational attraction between Earth and the Moon causes tides on Earth . The same effect on the Moon has led to its tidal locking : its rotation period is the same as the time it takes to orbit Earth . As a result , it always presents the same face to the planet . As the Moon orbits Earth , different parts of its face are illuminated by the Sun , leading to the lunar phases ; the dark part of the face is separated from the light part by the solar terminator . 
