Final answer:
Planets are classified into terrestrial planets with compositions of rocks and metals like Earth, and jovian planets dominated by gases like hydrogen and helium such as Jupiter and Saturn. This division suggests different formation conditions and processes across the solar system.
Step-by-step explanation:
The composition of planets within our solar system varies significantly, allowing us to classify them into two distinct categories. The terrestrial planets, which include Earth, Venus, Mars, and Mercury, are characterized by their rock and metal composition, with elements such as iron, silicon, and oxygen in the form of silicates being predominant. On the other hand, the jovian planets, Jupiter and Saturn, are comprised mainly of lighter elements such as hydrogen and helium, reflective of the solar nebula from which the solar system formed.
For instance, Earth's composition includes a solid iron core, a liquid iron outer core, a rocky mantle, and a crust, topped by a thin atmospheric layer. In contrast, Jupiter and Saturn have retained their gaseous components due to their strong gravitational pull. This differentiation between rocky terrestrial planets and gas-rich jovian planets indicates they may have formed under different conditions throughout the solar system's history.