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.
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 (Uranus and Neptune are ice giants). 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. (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 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 67 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.
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.
Jupiter is composed primarily of gaseous and liquid matter. It is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km (88,846 mi) at its equator. The 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 composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules. Because a helium atom has about four times as much mass as a hydrogen atom, the composition changes when described as the proportion of mass contributed by different atoms. Thus, the atmosphere is approximately 75% hydrogen and 24% helium by mass, with the remaining one percent of the mass consisting of other elements. The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. The atmosphere contains trace amounts of methane, water vapor, 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 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.Abundances of heavier inert gases in Jupiter's atmosphere are about two to three times that of the Sun.
Based on spectroscopy, Saturn is thought to be similar in composition to Jupiter, but the other giant planets Uranus and Neptune have relatively much less hydrogen and helium.Because of the lack of atmospheric entry probes, high-quality abundance numbers of the heavier elements are lacking for the outer planets beyond Jupiter.