Earth as a Planet: Observation, Measurement & Evidence

Earth's solid interior consists of crust, mantle, liquid outer core, and solid inner core. The atmosphere is layered above a surface dominated by oceans and moving tectonic plates. A magnetosphere surrounds the planet and interacts with the solar wind, while the biosphere exchanges carbon, oxygen, water, and nutrients with the atmosphere, ocean, and crust.

Seismic waves reveal internal layering, magnetic measurements map the dynamo-generated field, satellite geodesy measures plate motion, and atmospheric spectra determine gas composition. Geological records, fossils, isotope ratios, and climate proxies show how Earth's environment has changed over time.

Internal heat drives mantle convection and plate tectonics, which recycle crust and influence long-term carbon cycling. Motion in the electrically conducting liquid outer core sustains the magnetic dynamo. Solar energy powers weather and climate, while greenhouse gases regulate surface temperature. Life alters atmospheric chemistry, especially oxygen and carbon dioxide.

Seismology maps interior layering, satellite geodesy measures gravity and plate motion, paleomagnetism records magnetic-field history, and isotope systems constrain age and geochemical cycling. Remote observations of Earth from space provide the benchmark for interpreting unresolved exoplanets.