Earth tide, also known as solid tide or body tide, refers to the regular and periodic movement of the Earth's surface caused by the gravitational attraction of the Moon and the Sun. Some synonyms for Earth tide include lunar tide, solar tide, tidal deformation, and tidal movement. While these terms all describe the same phenomenon, they may refer to slightly different aspects of the Earth's motion. For example, lunar tide specifically refers to the influence of the Moon on the Earth's movement, while solar tide refers to the influence of the Sun. The term tidal deformation can also refer to the changes in the Earth's shape, caused by the gravitational forces of the Moon and Sun.