Definition
A terrestrial planet with a thin atmosphere is a rocky body surrounded by a greatly reduced gaseous envelope. This envelope limits heat transport, material movement and dynamic processes, creating a dry and weakly insulated environment.
Internal structure
The interior is organized into a metallic core, a silicate mantle and a solid crust. Mechanical properties vary gradually between these layers, generating slow internal motions and limited surface deformations.
Atmospheric envelope
The atmosphere consists of a thin layer of gases poor in water vapor. Its low density reduces insulation, weakens wind-driven erosion and produces a thermal regime largely determined by direct radiation and surface heat emission.
Surface and dynamics
The surface is dominated by rocks shaped by wind, dust deposits and traces of past or short-lived flows. The dynamics depend on thermal contrasts and generate local winds with marked seasonal variations.
Evolution
The evolution results from the progressive loss of primordial gases, decreasing internal activity and continuous interaction with radiation. This leads to atmospheric weakening and increasing surface dryness.
Limitations and interactions
The thin atmosphere limits protection against energetic particles, reduces the stability of surface water and favors the rapid dispersal of fine particles. Interactions between soil, ice and gas nonetheless remain essential for landscape structure.