Definition
A Gaïana-type planet is a terrestrial body with an atmosphere rich in nitrogen (N₂) and oxygen (O₂). These features allow the presence of liquid water and promote a balance between climate and geology.
Atmosphere
The atmosphere regulates surface temperature and protects against stellar radiation. Pressure keeps water in a liquid state and supports a hydrological cycle with precipitation, oceans, and evaporation. Circulation creates climate variation by latitude and altitude.
Water
The presence of liquid water on the surface is a defining trait. Oceans, covering a large portion of the surface, contribute to thermal regulation and the carbon cycle. Continental erosion supplies minerals to the seas, sustaining biogeochemical cycles.
Internal dynamics
Plate tectonics shape the surface, renew geological structures, and support the carbon cycle. Volcanism, earthquakes, and continental drift are manifestations of this activity, influencing long-term climate stability.
Habitability
Gaïana-type planets are prime candidates for extraterrestrial habitability. The abundance of oxygen in the atmosphere may result from biological or photochemical processes, indicating a favorable environment.
Detection
These planets can be identified through atmospheric spectroscopy. During transit in front of their star, their atmosphere filters starlight and reveals its chemical composition. The simultaneous presence of water vapor, carbon dioxide, and oxygen is an indicator of potential habitability.
Balance
Gaïana planets represent a balance between atmosphere, water, and geology. This arrangement provides stable conditions where life can arise and persist. Their study highlights the diversity of habitable worlds.