Earth tide

Summary

The Earth tide, or body tide, is the periodic deformation of the solid Earth caused by the tidal force of the Moon and the Sun. The ground rises and falls by a few tens of centimetres twice a day, and gravity and the direction of the vertical change slightly. Its size is measured by the Love numbers, which tell how elastic the Earth is as a whole. Earth tides must be removed from precise geodetic and gravity measurements, and they are a probe of the Earth's interior.