From largest to smallest, based on total circumference, the planets that make up this solar system are Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury. Any publication that lists Pluto as a planet is out of date. Astronomers now consider Pluto a dwarf planet.
The smallest four planets, and the dwarf planet Pluto, are the only ones in this solar system known to possess rocky surfaces. Astronomers refer to the larger four planets as gas giants due to their thick, gaseous atmospheres.
In addition to Pluto there are also four other dwarf planets caught in orbits around the sun. These are Ceres, Haumea, Makemake and Eris. The planets and dwarf planets also have their own orbiting bodies. As of 2014 there are 176 identified moons in the solar system.
Jupiter's moon system is the largest, with 63 known moons orbiting the gas giant. Astronomers think Saturn's rings are composed of the remnants from former orbiting moons that collided with one another and eventually formed the particulate discs that form the recognizable rings. Astronomers confirm that outside this solar system, as of 2014 there are 1,523 exo-planets orbiting distant stars, all varying in size, composition and orbital distance from their parent star.