Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times Earth. It only has one-eighth the average density of Earth; however, Saturn is over 95 times more massive with its larger volume. Saturn is named after the Roman god of wealth and agriculture; its astronomical symbol (♄) represents the god's sickle. Saturn's interior is most likely composed of a core of iron-nickel and rock (silicon and oxygen compounds). Its core is surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and finally, a gaseous outer layer. Saturn has a pale yellow hue due to ammonia crystals in its upper atmosphere.
The planet's most famous feature is its prominent ring system, composed mostly of ice particles with a smaller amount of rocky debris and dust. At least 82 moons are known to orbit Saturn, of which 53 are officially named; this does not include the hundreds of moonlets in its rings. Although less massive, Titan, Saturn's largest moon and the second largest in the Solar System, is larger than the planet Mercury and is the only moon in the Solar System to have a substantial atmosphere.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets, and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger than the smallest planet, Mercury.
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and – according to the International Astronomical Union but not all planetary scientists – has cleared its neighboring region of planetesimals.