The Sun’s gravity holds the inner planets tightly as they revolve around the Sun. The orbits of Mercury, Venus, Earth, and Mars revolve faster than the outer planets because they have less distance to travel. They revolve around the Sun all within a relatively flat plane.

The inner planets are rock and are relatively small bodies. They don’t have more than 2 satellites (Mars), with Venus and Mars having none. Mercury and Venus rotate on their axis slower than any of the other planets. Venus is the only planet that rotates clockwise, the other planets rotate on their axis counterclockwise. Mercury has a very eccentric orbit, similar to Pluto as it revolves around the Sun. The inner planets do not have any rings like the gas giants.