<Li> water (H O) </Li> <Li> ammonium hydrosulfide (NH SH) </Li> <P> Jupiter is the fifth planet from the Sun and the largest in the Solar System . It is a giant planet with a mass one - thousandth that of the Sun, but two - and - a-half times that of all the other planets in the Solar System combined . Jupiter and Saturn are gas giants; the other two giant planets, Uranus and Neptune are ice giants . Jupiter has been known to astronomers since antiquity . The Romans named it after their god Jupiter . When viewed from Earth, Jupiter can reach an apparent magnitude of − 2.94, bright enough for its reflected light to cast shadows, and making it on average the third - brightest object in the night sky after the Moon and Venus . </P> <P> Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules . It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well - defined solid surface . Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it has a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries . A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope . Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere . Jupiter has at least 69 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610 . Ganymede, the largest of these, has a diameter greater than that of the planet Mercury . </P>

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