Planets with a dense core:
* Rocky planets (like Earth, Mars, Venus): These planets typically have a dense metallic core (iron and nickel) surrounded by a less dense mantle (rock) and a thin crust. The pressure from gravity compresses the core, making it denser.
* Gas giants (like Jupiter, Saturn): While they don't have a solid core in the traditional sense, they have a very dense core of heavy elements surrounded by layers of hydrogen and helium. The pressure from gravity compresses the core, making it incredibly dense.
Planets without a dense core (or with a less pronounced density difference):
* Some exoplanets: There are exoplanets that are very large but composed of lighter elements like hydrogen and helium. These planets may have a less pronounced density difference between their core and outer layers.
* Planets with a more uniform composition: Planets that are formed primarily from a single type of material might have a more uniform density throughout, although the core will still be slightly denser due to pressure.
Important Note: The "core" of a planet isn't always a solid sphere. For gas giants, the core is more like a region of immense pressure where heavier elements are concentrated.
So, while it's common for planets to have a denser core, it's not a universal rule. The density distribution within a planet depends on its composition and the pressure from its gravity.
