the core of planets
The planetary core primary consists of the innermost layer(s) of a planet; which may be composed of solid and liquid layers.Cores of specific planets may be entirely solid or entirely liquid. In the Solar System, core size can range from about 20% (Moon) to 85% of a planet's radius (Mercury).
Gas giants also have cores, though the composition of these are still a matter of debate and range in possible composition from traditional stony/iron, to ice or to fluid metallic hydrogen. Gas giant cores are proportionally much smaller than those of terrestrial planets, though theirs can be considerably larger than the Earth's nevertheless; Jupiter has one 10–30 times heavier than Earth, and exoplanet HD149026 b has a core 67 times the mass of the Earth.