Jupiter

Jupiter

Jupiter's Statistics Mass (kg) : 1.900e+27 Mass (Earth = 1) : 3.1794e+02 Equatorial radius (km) : 71,492 Equatorial radius (Earth = 1) : 1.1209e+01 Mean density (gm/cm^3) : 1.33 Mean distance from the Sun (km) : 778,330,000 Mean distance from the Sun (Earth = 1) : 5.2028 Rotational period (days) : 0.41354 Orbital period (days) : 4332.71 Mean orbital velocity (km/sec) : 13.07 Orbital eccentricity : 0.0483 Tilt of axis (degrees) : 3.13 Orbital inclination (degrees) : 1.308 Equatorial surface gravity (m/sec^2) : 22.88 Equatorial escape velocity (km/sec) : 59.56 Visual geometric albedo : 0.52 Magnitude (Vo) : -2.70 Mean cloud temperature : -1210C Atmospheric pressure (bars) : 0.7 Detection Method : Normal Sight Year Discovered : Prehistory

The king of planets is aptly named because it not only has the most dymanic atmospheric motion, but also the most riveting cloud patterns and storms, and the most majestic appearance of the giant planets. The dramatic appearance of Jupiter stems partially because the composition of Jupiter's atmosphere includes complicated molecules such as ammonia and methane, as well as simple molecules such as helium, hydrogen, and sulfur. The composition also includes exotic molecules such as germain. The atmosphere of Jupiter is only a narrow surface layer, compared to the vast interior of the planet. The three clouddecks of Jupiter are to be found at different levels in the troposphere, while hazes of smog can be found higher in the atmosphere. Jupiter is not much changed from its early evolution out of the early solar nebula, and in fact, may still be forming!

Jupiter's Interior

Jupiter's composition is mainly hydrogen and helium. In contrast to planetary bodies covered with a hard surface crust (the Earth, for example), the jovian surface is gaseous-liquid, rendering the boundary between the atmosphere and the planet itself almost indistinguishable. Below the roughly 1000-kilometer-thick atmosphere, a layer of liquid hydrogen extends to a depth of 20,000 kilometers. Even deeper, it is believed that there is a layer of liquid metallic hydrogen at a pressure of 3 million bars. The planet core is believed to comprise iron-nickel alloy, rock, etc., at a temperature estimated to exceed 20,000C.

Jupiter's Clouds

Every day is a cloudy day on Jupiter, the Solar System's reigning gas giant. This 3-dimensional visualization presents a simplified model view from between Jovian cloud decks based on imaging and spectral data recorded by the Galileo spacecraft. The separation between the cloud layers and the height variations have been exaggerated. The upper cloud layer is haze a few tens of miles thick. Heights in the lower cloud layers have been color coded; light bluish clouds are high and thin, reddish clouds are low, and white clouds are high and thick. Streaks in the lower layer suggestively lead to a dark blue area, a relatively clear, dry region similar to the site where Galileo's atmospheric probe made the first entry into a gas giant planet's atmosphere on December 7th, 1995.

Ring of Jupiter

The ring of Jupiter was discovered by Voyager 1 in March of 1979. This image was taken by Voyager 2 and has been pseudo colored. The Jovian ring is about 6,500 kilometers (4,000 miles) wide and probably less than 10 kilometers (6.2 miles) thick.

Jupiter's Moons

Ganymede

Ganymede is the seventh and largest satellites of Jupiter's . Ganymede is the third of the Galilean moons. orbit: 1,070,000 km from Jupiter and It's diameter: 5262 km, and its mass is : 1.48e23 kg Ganymede was a Trojan boy of great beauty whom Zeus carried away to be cup bearer to the gods. Discovered by Galileo and Marius in 1610.

Io

Looking like a giant pizza covered with melted cheese and splotches of tomato and ripe olives, Io is the most volcanically active body in the solar system. Volcanic plumes rise 300 kilometers (190 miles) above the surface, with material spewing out at nearly half the required escape velocity. A bit larger than Earth's moon, Io is the third largest of Jupiter's moons, and the fifth one in distance from the planet.

Planetary Moon Io

Although Io always points the same side toward Jupiter in its orbit around the giant planet, the large moons Europa and Ganymede perturb Io's orbit into an irregularly elliptical one. Thus, in its widely varying distances from Jupiter, Io is subjected to tremendous tidal forces. These forces cause Io's surface to bulge up and down (or in and out) by as much as 100 meters (330 feet)! Compare these tides on Io's solid surface to the tides on Earth's oceans. On Earth, in the place where tides are highest, the difference between low and high tides is only 18 meters (60 feet), and this is for water, not solid ground!

This tidal pumping generates a tremendous amount of heat within Io, keeping much of its subsurface crust in liquid form, seeking any available escape route to the surface to relieve the pressure. Thus, the surface of Io is constantly renewing itself, filling in any impact craters with molten lava lakes and spreading smooth new floodplains of liquid rock. The composition of this material is not yet entirely clear, but theories suggest that it is largely molten sulfur and its compounds (which would account for the varigated coloring) or silicate rock (which would better account for the apparent temperatures, which may be too hot to be sulfur). Sulfur dioxide is the primary constituent of a thin atmosphere on Io. It has no water to speak of, unlike the other, colder Galilean moons. Data from the Galileo spacecraft indicates that an iron core may form Io's center, thus giving Io its own magnetic field.

Io's orbit, keeping it at more or less a cozy 422,000 kilometers (262,000 miles) from Jupiter, cuts across the planet's powerful magnetic lines of force, thus turning Io into a electric generator. Io can develop 400,000 volts across itself and create an electric current of 3 million amperes. This current takes the path of least resistance along Jupiter's magnetic field lines to the planet's surface, creating lightning in Jupiter's upper atmosphere.

As Jupiter rotates, it takes its magnetic field around with it, sweeping past Io and stripping off about 1,000 kilograms (1 ton) of Io's material every second! This material becomes ionized in the magnetic field and forms a doughnut-shaped cloud of intense radiation referred to as a plasma torus. Some of the ions are pulled into Jupiter's atmosphere along the magnetic lines of force and create auroras in the planet's upper atmosphere. It is the ions escaping from this torus that inflate Jupiter's magnetosphere to over twice the size we would expect.

Europa

Europa is a strange looking moon of Jupiter with a large number of intersecting features. It is unlike Callisto and Ganymede with their heavily cratered crusts. Europa has almost a complete absence of craters as well as almost no vertical relief.

As one scientist put it, the features "might have been painted on with a felt marker". There is a possibility that Europa may be internally active due to tidal heating at a level one-tenth or less that of Io. Models of Europa's interior show that beneath a thin 5 km (3 miles) crust of water ice, Europa may have oceans as deep as 50 km (30 miles) or more. The visible markings on Europa could be a result of global expansion where the crust could have fractured, filled with water and froze.

Callisto

With a diameter of over 4,800 km (2,985 miles), Callisto is the third largest satellite in the solar system and is almost the size of Mercury. Callisto is the outermost of the Galilean satellites, and orbits beyonds Jupiter's main radiation belts. It has the lowest density of the Galilean satellites (1.86 grams/cubic centimeter).

Its interior is probably similar to Ganymede except the inner rocky core is smaller, and this core is surrounded by a large icy mantle. Callisto's surface is the darkest of the Galileans, but it is twice as bright as our own Moon.

Landscape

Ganymede, Io, Europa, and Callisto orbit around Jupiter