what are the terrestrial planets
The terrestrial planets Mercury, Venus, Earth, and Mars, sizes to scale. A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e.Mercury, Venus, Earth, and Mars.The terms terrestrial planet and telluric planet are derived from Latin words for Earth (Terra and Tellus), as these planets are, in terms of composition, Earth-like.he Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere.