Planet

A planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting a star or stellar remnant that is enormous enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion, and has cleared its neighboring region of planetesimals.

The term planet is an antique one having ties to history, science, myth, and religion. The planets were originally seen as a divine attendance; as emissaries of the gods. Even today, many people continue to believe the movement of the planets affects their lives, although such causation is rejected by the scientific community. As scientific knowledge advanced, the human awareness of the planets changed over time, incorporating a number of disparate objects. Even now there is no recognized definition of what a planet is. In 2006, the IAU formally adopted a resolution defining planets within the Solar System. This definition has been both praised and criticize, and remains disputed by some scientists.

Under IAU definitions, there are eight planets in the Solar System (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and 270 further solar ones. The Solar System also contains at slightest three dwarf planets (Ceres, Pluto, and Eris). Many of these planets are orbited by one or more moons, which can be superior than small planets. Planets are usually divided into two main types: large, low-density gas giants and smaller, rocky terrestrials.