Where Did the Sea Come From?

Earth's oceans formed through a series of cosmic and geological processes:

1. Nebula Formation: Solar system condensed from a gas/dust cloud.
2. Accretion & Differentiation: Planetesimals collided, forming Earth; heat from impacts and radioactivity caused melting and layering.
3. Giant Impact: A Mars-sized body (Theia) struck Earth ~4.5 billion years ago, ejecting debris that formed the Moon and a vapor-rich disk.
4. Volatile Release & Condensation: Water vapor and other gases from the disk and Earth's interior condensed as the planet cooled, forming liquid water on the surface.
5. Plate Tectonics: Ongoing crustal movement reshaped ocean basins and continents into modern geography.

Thus, the seas are the result of planetary accretion, cosmic collisions, outgassing, condensation, and tectonic evolution.