Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant 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 is the third-brightest natural object in the Earth's night sky after the Moon and Venus. It has been observed since pre-historic times and is named after the Roman god Jupiter.
Jupiter is primarily composed of hydrogen, but helium comprises one quarter of its mass and one tenth of its volume. It likely has a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. The on-going contraction of its interior generates heat greater than the amount received from the Sun. 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, with turbulence and storms along their interacting boundaries. A prominent result of this 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 almost a hundred known moons and possibly many more, 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.
Size and Distance :
With a radius of 43,440.7 miles (69,911 kilometers), Jupiter is 11 times wider than Earth. If Earth were the size of a nickel, Jupiter would be about as big as a basketball. From an average distance of 484 million miles (778 million kilometers), Jupiter is 5.2 astronomical units away from the Sun. One astronomical unit (abbreviated as AU), is the distance from the Sun to Earth. From this distance, it takes Sunlight 43 minutes to travel from the Sun to Jupiter. Planets are shown in the correct order of distance from the Sun and with the correct relative orbital distances. The sizes of the bodies is greatly exaggerated for emphasis. Credit: NASA/Moore Boeck
Orbit and Rotation :
Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the Sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days). Its equator is tilted with respect to its orbital path around the Sun by just 3 degrees. This means Jupiter spins nearly upright and does not have seasons as extreme as other planets do.
Physical characteristics :
Jupiter is one of the four gas giants, being primarily composed of gas and liquid rather than solid matter. It is the largest planet in the Solar System, with a diameter of 142,984 km (88,846 mi) at its equator. The average density of Jupiter, 1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets.
Jupiter's upper atmosphere is about 90% hydrogen and 10% helium by volume. Since helium atoms are more massive than hydrogen atoms, Jupiter's atmosphere is approximately 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements. The atmosphere contains trace amounts of methane, water vapour, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. The outermost layer of the atmosphere contains crystals of frozen ammonia. Through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found. The interior of Jupiter contains denser materials—by mass it is roughly 71% hydrogen, 24% helium, and 5% other elements.
The atmospheric proportions of hydrogen and helium are close to the theoretical composition of the primordial solar nebula. Neon in the upper atmosphere only consists of 20 parts per million by mass, which is about a tenth as abundant as in the Sun. Helium is also depleted to about 80% of the Sun's helium composition. This depletion is a result of precipitation of these elements into the interior of the planet.
Based on spectroscopy, Saturn is thought to be similar in composition to Jupiter, but the other giant planets Uranus and Neptune have relatively less hydrogen and helium and relatively more ices and are called ice giants.
Internal structure :
Before the early 21st century, most scientists expected Jupiter to either consist of a dense core, a surrounding layer of liquid metallic hydrogen (with some helium) extending outward to about 80% of the radius of the planet, and an outer atmosphere consisting predominantly of molecular hydrogen, or perhaps to have no core at all, consisting instead of denser and denser fluid (predominantly molecular and metallic hydrogen) all the way to the center, depending on whether the planet accreted first as a solid body or collapsed directly from the gaseous protoplanetary disk. When the Juno mission arrived in July 2016, it found that Jupiter has a very diffuse core that mixes into its mantle. A possible cause is an impact from a planet of about ten Earth masses a few million years after Jupiter's formation, which would have disrupted an originally solid Jovian core. It is estimated that the core is 30–50% of the planet's radius, and contains heavy elements 7–25 times the mass of Earth.
Above the layer of metallic hydrogen lies a transparent interior atmosphere of hydrogen. At this depth, the pressure and temperature are above hydrogen's critical pressure of 1.2858 MPa and critical temperature of only 32.938 K. In this state, there are no distinct liquid and gas phases—hydrogen is said to be in a supercritical fluid state. It is convenient to treat hydrogen as gas extending downward from the cloud layer to a depth of about 1,000 km, and as liquid in deeper layers. Physically, there is no clear boundary—the gas smoothly becomes hotter and denser as depth increases. Rain-like droplets of helium and neon precipitate downward through the lower atmosphere, depleting the abundance of these elements in the upper atmosphere. Rainfalls of diamonds have been suggested to occur, as well as on Saturn and the ice giants Uranus and Neptune.
The temperature and pressure inside Jupiter increase steadily inward, this is observed in microwave emission and required because the heat of formation can only escape by convection. At the pressure level of 10 bars (1 MPa), the temperature is around 340 K (67 °C; 152 °F). The hydrogen is always supercritical (that is, it never encounters a first-order phase transition) even as it changes gradually from a molecular fluid to a metallic fluid at around 100–200 GPa, where the temperature is perhaps 5,000 K (4,730 °C; 8,540 °F). The temperature of Jupiter's diluted core is estimated at around 20,000 K (19,700 °C; 35,500 °F) or more with an estimated pressure of around 4,500 GPa.
Structure of Jupiter
:Jupiter's appearance is a tapestry of colorful cloud bands and spots. The gas planet likely has three distinct cloud layers in its "skies" that, taken together, span about 44 miles (71 kilometers). The top cloud is probably made of ammonia ice, while the middle layer is likely made of ammonium hydrosulfide crystals. The innermost layer may be made of water ice and vapor.
The vivid colors you see in thick bands across Jupiter may be plumes of sulfur and phosphorus-containing gases rising from the planet's warmer interior. Jupiter's fast rotation—spinning once every 10 hours—creates strong jet streams, separating its clouds into dark belts and bright zones across long stretches.
With no solid surface to slow them down, Jupiter's spots can persist for many years. Stormy Jupiter is swept by over a dozen prevailing winds, some reaching up to 335 miles per hour (539 kilometers per hour) at the equator. The Great Red Spot, a swirling oval of clouds twice as wide as Earth, has been observed on the giant planet for more than 300 years. More recently, three smaller ovals merged to form the Little Red Spot, about half the size of its larger cousin. Scientists do not yet know if these ovals and planet-circling bands are shallow or deeply rooted to the interior.
Facts about Jupiter :
Jupiter is the fourth brightest object in the solar system.
Only the Sun, Moon and Venus are brighter. It is one of five planets visible to the naked eye from Earth.
The ancient Babylonians were the first to record their sightings of Jupiter.
This was around the 7th or 8th century BC. Jupiter is named after the king of the Roman gods. To the Greeks, it represented Zeus, the god of thunder. The Mesopotamians saw Jupiter as the god Marduk and patron of the city of Babylon. Germanic tribes saw this planet as Donar, or Thor.
Jupiter has the shortest day of all the planets.
It turns on its axis once every 9 hours and 55 minutes. The rapid rotation flattens the planet slightly, giving it an oblate shape.
Jupiter orbits the Sun once every 11.8 Earth years.
From our point of view on Earth, it appears to move slowly in the sky, taking months to move from one constellation to another.
Jupiter has unique cloud features.
The upper atmosphere of Jupiter is divided into cloud belts and zones. They are made primarily of ammonia crystals, sulfur, and mixtures of the two compounds.
The Great Red Spot is a huge storm on Jupiter.
It has raged for at least 350 years. It is so large that three Earths could fit inside it.
Jupiter’s interior is made of rock, metal, and hydrogen compounds.
Below Jupiter’s massive atmosphere (which is made primarily of hydrogen), there are layers of compressed hydrogen gas, liquid metallic hydrogen, and a core of ice, rock, and metals.
Jupiter’s moon Ganymede is the largest moon in the solar system.
Jupiter’s moons are sometimes called the Jovian satellites, the largest of these are Ganymeade, Callisto Io and Europa. Ganymeade measures 5,268 km across, making it larger than the planet Mercury.
Jupiter has a thin ring system.
Its rings are composed mainly of dust particles ejected from some of Jupiter’s smaller worlds during impacts from incoming comets and asteroids. The ring system begins some 92,000 kilometres above Jupiter’s cloud tops and stretches out to more than 225,000 km from the planet. They are between 2,000 to 12,500 kilometres thick.
Eight spacecraft have visited Jupiter.
Pioneer 10 and 11, Voyager 1 and 2, Galileo, Cassini, Ulysses, and New Horizons missions. The Juno mission is its way to Jupiter and will arrive in July 2016. Other future missions may focus on the Jovian moons Europa, Ganymede, and Callisto, and their subsurface oceans.