The gravitational pull of the moon is responsible for the change in tides. The part of the Earth facing the moon is most exposed to its gravitational pull, which affects the water in the oceans. It is literally pulled up and high tide occurs on the side facing the moon. A second force acts on the opposite side of the Earth: centrifugal force. As the Earth and the moon rotate around a common axis, the water is literally hurled outwards like a carousel. This creates a second tidal crest. These two tidal crests always move around the Earth with the moon. Wherever there is no tide, there is low tide. However, the moon does not need exactly 24 hours to travel around the Earth. The moon's journey takes a little longer, namely 24 hours and 51 minutes.
This is why the high and low tide times shift by about an hour every day.
