Solid Earth refers to "the Earth beneath our feet" or , the planet's solid surface and its interior. It contrasts with the Earth's fluid envelopes, the atmosphere and hydrosphere (but includes the ocean basin), as well as the biosphere and interactions with the sun. It includes the liquid core. Solid-earth science refers to the corresponding methods of study, a subset of Earth sciences, predominantly geophysics and geology, excluding aeronomy, atmospheric sciences, oceanography, hydrology, and ecology.