Jupiter

Planet Profile

Mass (kg)............................................1.90 x 10^27
Diameter (km)........................................142,800
Mean density (kg/m^3) ...............................1314
Escape velocity (m/sec)..............................59500

Average distance from Sun (AU).......................5.203
Rotation period (length of day in Earth hours).........9.8
Revolution period (length of year) (in Earth years)..11.86

Obliquity (tilt of axis) (degrees)...................3.08
Orbit inclination (degrees)..........................1.3
Orbit eccentricity...................................0.048

Mean surface temperature (K).........................120 (cloud tops)

Visual geometric albedo..............................0.44
Atmospheric components...............................90% hydrogen,
                                                     10% helium, 
                                                       .07% methane
Rings................................................Faint ring.
		      Infrared spectra imply dark rock fragments.

Full Disk

Jupiter is a "gas giant"; all gas giants are similar to Jupiter in composition. Jupiter's diameter is 11 times Earth's diameter and 20% larger than Saturn's, making it the largest planet in the solar system. Gas giants are also very much larger than terrestrial planets. This color-enhanced image of Jupiter was taken by Voyager 1.

Jovian System

Voyager 1 took this photo of Jupiter and two of its satellites, Io on the left and Europa on the right. Io is about 350,000 km (217,000 mi) above Jupiter's Great Red Spot; Europa is about 600,000 km (372,000 mi) above Jupiter's clouds. Although both satellites have about the same brightness, Io's color is different from Europa's. Io's equatorial region shows two shades of red, possibly indicating different surface materials.

The Great Red Spot

The colorful, wavy cloud pattern to the left of the Red Spot is a region of extraordinarily complex wave motion. This dramatic view of the Great Red Spot and its surroundings was taken February 25, 1979, when Voyager 1 was 9.2 million km (5.7 million mi) from Jupiter. An atmospheric system larger than Earth and more than 300 years old, the Great Red Spot remains a mystery. Swirling, storm-like features possibly associated with wind shear can be seen both to the left and above the Red Spot.

White Cloud

This mosaic of the Great Red Spot was taken by the Voyager 2 spacecraft. It shows that the region changed significantly since the Voyager 1 encounter four months earlier. Around the northern boundary a white cloud is seen, which extends east of the region. The presence of this cloud prevents small cloud vertices from circling the spot in the manner seen in the Voyager 1 encounter.

Red Spot Turbulence

The turbulence surrounding the Great Red Spot is shown here in enhanced color, which tends to emphasize red and blue at the expense of green. Near the bottom you can see one of three oval cloud systems that formed nearly 40 years ago. The distance from top to bottom of this picture is 24,000 km (15,000 mi).

East of the Red Spot

The region just east of the Red Spot is seen here in greatly exaggerated color. The colors do not represent the true hues seen in the Jovian atmosphere but have been produced by special computer processing to enhance subtle variations in both color and shading. A close-up of one of the boundaries between the latitudinal cloud bands shows interaction between the bands.

Large Brown Oval

This large brown oval could be an opening in the upper cloud deck where warmer cloud levels may exist. Features of this sort are not rare on Jupiter and have an average lifetime of one to two years. Above the feature is the pale orange North Temperate Belt, bounded on the south by the high-speed North Temperate Current with winds of 120 m/s (260 mi/hr). The range to Jupiter, on March 2, 1979 when this photograph was taken, was 4.0 million km (2.5 million mi).

Ring System

Data from the Pioneer 10 and 11 spacecraft suggested that a ring system around the giant planet Jupiter existed; this was confirmed by the Voyager flybys. This image was taken by Voyager 2 looking back at the rings from inside Jupiter's shadow. The ring is very bright because it is composed of fine dust, which scatters light efficiently in this viewing geometry. The picture shows the main ring 7000 km (4350 mi) wide, with a broad, thick "halo" inside it.

Global Mosaic

Io's surface materials are rich in sulfur compounds. Its volcanism is driven by tidal stresses induced by Jupiter and the next satellite out, Europa. Black lava lakes dot Io's surface, some of them as hot as 200 øC (392 øF). Io measures 3630 km (2178 mi) in diameter.

Io's South Pole

Numerous volcanic features dot the south polar region of Io, including lava flows around calderas. Scientists think that the bright patches seen here may be due to sulfur dioxide ice and gas jetted from fractures in the surface.

Explosion on Io

A volcanic explosion can be seen silhouetted against dark space over Io's brilliant limb. Solid material was blasted to an altitude of about 160 km (100 mi), requiring an ejection velocity from the volcanic vent of about 1920 km (1200 mi) per hour. Io appears to be far more volcanically active than Earth.

Erupting Volcano

The blue and white protrusion visible on the limb is an eruption of Volcano Loki. This picture of Io was taken by the Voyager 2 spacecraft in July 1979, during its closest approach to Jupiter's satellite.

Volcanic Plume

These images were specially processed to show detail both on the surface of Io and in the faint plume. This volcano is named Prometheus. The eruption is thought to be driven by sulfur dioxide gas that is heated by molten sulfur and driven out of the vent at a velocity of about 1/2 km (0.3 mi) per second. The plume reaches an altitude of about 50 km (30 mi), spreading out over a diameter of about 300 km (190 mi).

Volcanic Eruption

The eruption seen here is coming from the volcano named Prometheus. The eruption is roughly 300 km (190 mi) in diameter and 50 km (30 mi) high. It appears like a giant black spider standing in a white ring on the surface of Io, located at the center of the curve of the limb.

Venting Gases

On the floor of the northern-most caldera in this image lies a bright blue patch. Scientists believe that patch may be gas clouds spewing from volcanic vents. The clouds may condense to form extremely fine particles that appear blue. Because Voyager 1's infrared spectrometer discovered sulfur dioxide on Io, it is possible that sulfur dioxide is the main ingredient of the clouds. Such clouds would rapidly freeze and snow back to the surface. It is also possible that dark areas on the caldera floors are pools of molten sulfur, a very dark form of sulfur.

South Pole

Scientists believe that the surface of Europa is made up of ice mixed with rocky material. Complex ridges tracing cuspate forms testify to tectonic processes ongoing on this world. This image shows the area along the terminator extending into the south polar region.

Europa in Color

Europa, close in size to our Moon, is thought to have an ice surface 100 km (62 mi) thick, which overlies a silicate surface. The complex array of streaks indicates that the crust has been fractured. The lack of mountains or craters on its bright limb is consistent with an ice surface. In contrast to its icy neighbors, Ganymede and Callisto, Europa has few impact craters. One possible candidate is the small feature near the center of this image with radiating rays and a bright circular interior. The relative absence of features and low topography suggests the crust is young.

Limb of Ganymede

The interior of Ganymede is thought to consist of a rocky core about the size of our Moon and to be surrounded by a thick covering of ice roughly equal in mass. Because the surface of Ganymede is made of ice, mountainous terrain would eventually collapse. Complex intersecting avenues of dark and bright terrains record multiple episodes in which the crust was fractured and reformed by icy volcanic fluids. About the size of Mercury, Ganymede is 5280 km (3168 mi) in diameter.

Tectonic Patterns

On Ganymede, complex tectonic patterns have formed on the icy crust. Two explanations for their creation have been offered. First, these patterns are produced by tectonic forces that squeeze and wrinkle the surface. These patterns resemble dikes on Earth so that a second possibility is that these patterns might have formed when liquid water rose through the closely spaced faults near the surface and froze. The area shown is about 100 km (62 mi) on a side.

Halo Crater

A bright halo impact crater with fresh ejecta is visible here. Behind the crater is bright grooved terrain, which may be the result of shearing of surface materials along fault planes. The dark background material is the ancient heavily cratered terrain; the oldest material on Ganymede. Features as small as 6 km (4 mi) across are visible in this image.

Ancient Terrain

This color reconstruction of part of the northern hemisphere of Ganymede was made from pictures taken at a range of 313,000 km (194,000 mi). It shows a dark, densely cratered area bound on the south by lighter, less cratered grooved terrain. Dark areas are believed to be the oldest surface on Ganymede. Numerous craters, many with central peaks, are visible. The large bright circular features have little relief and are probably the remnants of old, large craters. The closely spaced, arcuate features are similar to other features on Ganymede that surround large impact basins.

Impact Scar

Callisto, composed of rock and ice, is covered with numerous impact craters. The largest of these is Valhalla Basin, a 2748-km (1650-mi) multi-ring impact basin near the top of the image. Craters on Callisto appear as bright and dark spots whose morphology changes. Newer craters appear as sharply defined bright and dark spots. Over time older craters appear as more diffuse splotches.

Impact Craters

This Voyager image is of Callisto, Jupiter's fourth large satellite. It is one of the Galilean satellites, so named because Galileo saw them when he first turned his telescope toward Jupiter. Callisto shows a surface saturated with impact scars attesting to the great age of this icy world.

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