Inner planets are the planets that are located in the asteroid belt. There are four inner planets- Mercury, Venus, Earth, and Mars. These are also called terrestrial planets.

These planets are rocky due to the following reasons:

a. The terrestrial planets were formed in the close vicinity of the parent star where it was warm for the gases to condense to solid particles.

b. The solar winds were most intense near to the sun. So it blew off most of the gas and dust away from the terrestrial planets.

c. Moreover, these planets are small and their lower gravity could not hold the escaping gases.

The gaseous planets are Jupiter, Saturn, Uranus, and Neptune. They are called gaseous planets because they are located from the sun.