Inner Planets vs. Outer Planets. Ashlynn Hunkin Period 2. Inner planets.
The four inner planets or terrestrial planets have dense, rocky compositions. They have few or no moons, and no ring systems. Three of the four inner planets (Venus, Earth, and Mars) have atmospheres substantial enough to generate weather, all have impact craters and tectonic surface features such as rift valleys and volcanoes. The inner planets orbit closest to the sun.
The four outer planets, Neptune, Uranus, Saturn, and Jupiter, collectively make up 99% of the mass known to the sun’s orbit. They are also known as gas giants. All four of the gas giants have giants. The outer planets are mostly composed of gas, at the center they have one scientists refer to as a rocky core. The rocky core however is composed of heavy liquid metals. The outer planets are also much larger then the inner planets and have many moons and ring systems.
The main reason that Pluto isn’t a planet is because it wasn’t able to “clear its neighborhood” . As planets form, they become the dominant gravitational body in their orbit in the solar system. As they interact with other objects, they either consume them, or sling them away with their gravity. Pluto isn’t able to do this, therefore Pluto is considered a dwarf planet.