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The Jupiter Portal
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with a mass slightly less than one-thousandth of the Sun but is two and a half times the mass of all the other planets in our 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 and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, 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; it may also have a rocky core of heavier elements. Because of its rapid rotation, Jupiter'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 the planet is a faint planetary ring system and a powerful magnetosphere. There are also at least 63 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.
, or as Greek Ἰώ)
is the innermost of the four Galilean moons
of the planet Jupiter
and, with a diameter
of 3,642 kilometres (2,263 mi), the fourth-largest moon
in the Solar System
. It was named after Io
, a priestess of Hera
who became one of the lovers of Zeus
With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Some of these peaks are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost.
Ouyang Ziyuan (Chinese: 欧阳自远; pinyin: Ōuyáng Zìyuǎn) , born in 1935, Ji'an, Jiangxi Province, People's Republic of China, is a cosmochemist and geochemist, Research professor, Institute of Geochemistry, Chinese Academy of Sciences.
With a degree in geology and a doctorate in mineral deposits and geochemistry, he spent many years in deep mines. He later studied nuclear physics and worked in a particle accelerator laboratory. Thus, he put forward the hypothesis of formation of iron meteorites, evolution model of forming Jilin meteorites and theory of multi-stage cosmic ray radiation history. His works include Celestial Chemistry, and he published more than 160 treatises. He was elected a Member of the Chinese Academy of Sciences in 1991. As one of the most prominent Chinese experts in geological research on underground nuclear test and extraterrestrial materials, he was naturally the first to advocate not only the exploitation of the known huge lunar reserves of metals such as iron, but also the mining of lunar helium-3 as an ideal fuel for nuclear fusion power plants.