Similarities between the earth and Mercury, Venus and Mars (terrestrial planets).

In terms of structure, the planets of our solar system can be divided into three main groups:

1. Gas planets;

2. Rigid planets, consisting of silicates and metals;

3. Ice planets.

The planets of the second, or terrestrial, group have many similarities. For example, they all consist of three main parts: the core, the mantle, and the hard shell. The chemical composition of most of the rocks is also identical: they consist of oxides (contain oxygen), iron, silicon, etc. Outside our solar system, such planets have also been discovered.