Definition
An ice giant planet is a type of massive planet whose composition is dominated by volatile elements such as water, methane, and ammonia. Unlike gas giants, these planets contain a greater proportion of these components in icy or fluid form, although hydrogen and helium are also present. They lack a clearly defined solid surface.
Internal structure
The internal structure of an ice giant planet is layered. It typically consists of a dense central core, often rocky or metallic, surrounded by a mantle containing ices under high pressure, and an outer layer of mixed gases and fluids. The transition between these layers is gradual, depending on increasing pressure and temperature.
Atmosphere and dynamics
The atmosphere of ice giants mainly contains hydrogen, helium, and methane, the latter giving them a bluish hue. They can exhibit strong winds, cloud bands, and persistent weather systems. Atmospheric dynamics are influenced by rapid rotation and internal heat transfer.
Evolution and formation
Ice giant planets form in the outer regions of protoplanetary disks where temperatures allow for ice condensation. They can develop a massive core capable of attracting a modest gaseous layer. Their subsequent evolution depends on orbital environment, satellite capture, and interactions with other celestial bodies.
Differences from other planets
Unlike terrestrial planets, ice giants do not have a surface suitable for landing. Compared to gas giants, they are richer in heavy elements and possess a mantle dominated by volatiles. Their mass, density, and size vary depending on models and known examples.