Definition
Venus is an inner terrestrial planet composed mainly of silicates and metals. Its extremely dense atmosphere produces a unique radiative and thermal regime among rocky planets. Its high reflectivity is caused by continuous cloud layers.
Internal structure
The interior consists of an iron-nickel metallic core, a viscoelastic silicate mantle, and a solid crust. Seismological evidence suggests the absence of Earth-like plate tectonics, replaced by large-scale deformation and slow thermal recycling.
Surface and geology
The surface is dominated by volcanic products: basaltic plains, viscous domes, calderas and solidified flows. Linear fractures, tessera regions and large plateaus indicate persistent endogenous activity. Limited crater erosion reveals a relatively young surface. The distribution of forms reflects a balance between mantle upwellings, volcanism and thermal relaxation.
Atmosphere and composition
The atmosphere is composed mostly of carbon dioxide with a small fraction of nitrogen and sulfuric-acid aerosols. Cloud layers form a thick barrier trapping infrared radiation. The thermal structure yields nearly uniform temperatures regardless of lighting or latitude.
Climate and dynamics
The vertical temperature gradient, strengthened by infrared absorption, generates a runaway greenhouse regime. The upper atmosphere exhibits super-rotation, where winds travel far faster than the planet itself. Convective cells, wave patterns and quasi-stationary structures develop in the high clouds.
Rotation and orbital features
The planet rotates slowly in a retrograde direction. This motion, together with the viscoelastic behaviour of the upper atmosphere, affects wind distribution and internal dynamic stresses. Partial synchronisation between rotation and illumination cycles contributes to its energy balance.
Evolution and current state
Models indicate a gradual shift toward an environment dominated by greenhouse conditions during planetary evolution. The present surface derives from long volcanic phases and scattered tectonic reorganisations. Studies of Venus rely on radar mapping, spectroscopy and probe-based measurements.