The Terrestrial Planets. From top: Mercury, Venus, Earth and Mars. The planets Mercury, Venus, Earth, and Mars, are called terrestrial because they have a compact, rocky surface like Earth's terra firma. The terrestrial planets are the four innermost planets in the solar system.

Why do they call it inner planets?

In the inner Solar System, we find the “Inner Planets” – Mercury, Venus, Earth, and Mars – which are so named because they orbit closest to the Sun. In addition to their proximity, these planets have a number of key differences that set them apart from planets elsewhere in the Solar System.

How do you describe the inner planets?

Definition: The inner planets are the four planets which orbit closest to the sun in our solar system. All of them are solid, rocky planets. The nearest to the sun is Mercury, followed by Venus, Earth and Mars.