Jupiter, the largest planet in the Solar System, has a volume equal to more than 1,000 Earths. The fifth planet from the Sun is called a gas giant because it has no solid surface, being mainly composed of hydrogen and helium. It is believed to have liquid metallic hydrogen in its interior that generates the planet's intense magnetic field.
Photo: A true colour mosaic of Jupiter taken by the Cassini probe (NASA/JPL/Space Science Institute)
The largest planet is wracked by ancient storms.
BBC News reports on Galileo's plunge into Jupiter's atmosphere.
BBC News's Dr David Whitehouse reports on the Galileo entry probe's plunge into Jupiter and its early findings. NASA scientists said that the atmosphere contains ammonia, hydrogen sulphide and methane, a combination of smelly gases.
Sir Patrick Moore is amazed by the detail of Voyager 1's images.
Early in Voyager 1's mission, Sir Patrick Moore and his guest Dr Garry Hunt of University College London discussed some of the probe's findings, which included a ring around Jupiter and images of Jupiter's moons Amalthea, Callisto, Io, Europa and Ganymede. Since Sir Patrick and Dr Hunt spoke, Jupiter has been found to have three faint rings.
The early Solar System was a shooting gallery.
Professor Brian Cox explains how the orbiting gas giants may have caused an enormous asteroid and comet bombardment in the inner Solar System 3.6 billion years ago. Earth and the other planets were peppered by asteroids and comets.
Jupiter's atmosphere and immense gravity generate huge storms.
Professor Brian Cox looks at how weather systems are formed on the gas giant Jupiter. The planet's immense gravity and atmospheric pressure can transform gases into metallic liquid and generate enough energy to fuel the biggest storm in the Solar System.
Jupiter's moon Io is stretched and squashed.
Professor Brian Cox explains the incredible volcanism on Jupiter's moon Io.
Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth of that of the Sun but is two and a half times the mass of all the other planets in the Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets. The planet was known by astronomers of ancient times. The Romans named the planet after the Roman 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. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
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. It may also have a rocky core of heavier elements, but like the other gas giants, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it possesses 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. There are also at least 67 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of the planet Mercury.
Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.