General Knowledge - World Geography - Discussion

Pluto is no longer a planet. According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit. Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon, " is only about half the size of Pluto, while all the true planets are far larger than their moons.

"Superior planet" is used in reference to Mars, Jupiter, Saturn, (and later additions Uranus and Neptune) , which are farther from the Sun than the Earth is.

This classification is different from the terms inner and outer planet, which designate those planets which lie inside the asteroid belt and those that lie outside it, respectively. "Inferior planet" is also very different to minor planet or dwarf planet.