* Terrestrial Planets: These planets are primarily composed of rock and metal.
* Mercury: Mostly iron and nickel core, with a thin rocky mantle.
* Venus: Thick atmosphere, volcanic surface, with a rocky mantle and core.
* Earth: Rocky crust, mantle, and a liquid outer core with a solid inner core.
* Mars: Rocky surface with a core that is probably mostly iron and nickel.
* Gas Giants: These planets are mostly composed of gases, but they have a core.
* Jupiter: Mostly hydrogen and helium, with a core thought to be rocky and metallic.
* Saturn: Mostly hydrogen and helium, with a core thought to be rocky and metallic.
* Uranus: Mostly hydrogen and helium, with a core of ice and rock.
* Neptune: Mostly hydrogen and helium, with a core of ice and rock.
So, while the terrestrial planets are largely solid, even the gas giants have a solid core deep within their atmospheres.
Keep in mind that even the "solid" terrestrial planets have layers of varying density and composition, which is not just a single solid material.
