Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a giant planet with a mass one-thousandth of that of the Sun, but is two and a half times that of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn. Jupiter was known to astronomers of ancient times.The Romans named it after their god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough to cast shadows, and making it on average the third-brightest object in the night sky after the Moon and Venus.Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. Jupiter lacks a well-defined solid surface.
Jupiter has a faint planetary ring system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring. These rings appear to be made of dust, rather than ice as with Saturn's rings. The main ring is probably made of material ejected from the satellites Adrastea and Metis. Material that would normally fall back to the moon is pulled into Jupiter because of its strong gravitational influence. The orbit of the material veers towards Jupiter and new material is added by additional impacts. In a similar way, the moons Thebe and Amalthea probably produce the two distinct components of the dusty gossamer ring. There is also evidence of a rocky ring strung along Amalthea's orbit which may consist of collisional debris from that moon.
Artisitic Representation of NASA's Galileo Jupiter Probe.
Artisitic Representation of NASA's Galileo Jupiter Probe.
 Jupiter Moon IoCloseup of Jupiter's Volcanic Moon Io |  Jupiters Big Red Spot & CloudsView of Jupiter's Big Red Spot & Associated Storm Clouds |  Jupiter's MoonsArtworked Images of Jupiter's Biggest Moons Europa, Io, Ganymede & Callisto |
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 Jupiter's Pressure & TemperatureThis Cross-Section View Shows Estimated Temperatures & Pressures at Various Depths. |  Jupiter's Interior LayersThis Diagram Shows What Scientists Estimate to Lie Underneath Jupiter's Clouds |  Jupiter's MoonsArtworked Images of Jupiter's Biggest Moons Europa, Io, Ganymede & Callisto |
 Jupiter's Moon Io CrossingThis Image Taken by Galileo Probe of Io Orbiting Jupiter. |  Jupiter's Big Red SpotSuper Closeup of Jupiter's 300 Year Strom We Call The Red Spot |  Planet Earth Next to Big Red SpotArtistic Representation of How Earth Would Appear Next to The Big Red Spot |
 Jupiter's Moon EuropaCloseup of Europa's Icy Surface |  Jupiter's Moon Europa Cross-SectionArtistic Representation of Scientists Estimate is Beneath Europa's Icy Surface. |  Jupiter's Moon CallistoCallisto is the most heavily cratered object in the solar system. It is thought to be a long dead world, with hardly any geologic activity on its surface. In fact, Callisto is the only body greater than 1000 km in diameter in the solar system that has shown no signs of undergoing any extensive resurfacing since impacts have molded its surface. With a surface age of about 4 billion years, Callisto has the oldest landscape in the solar system |