Jupiter is the fifth planet from the Sun and is the largest one in the solar system. If Jupiter were hollow, more than
one thousand Earths could fit inside. It also contains more matter than all of the other planets combined. It has a mass of
1.9 x 1027
kg and is 142,800 kilometers (88,736 miles) across the equator. Jupiter possesses 28 known satellites,
four of which - Callisto, Europa, Ganymede and Io - were observed by Galileo
as long ago as 1610. Another 12 satellites have been recently discovered and given provisional designators until they are
officially confirmed and named. There is a ring system, but it is very faint and is totally invisible from the Earth. (The
rings were discovered in 1979 by Voyager 1.) The atmosphere is very deep, perhaps comprising the whole planet, and is somewhat
like the Sun. It is composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor and other
compounds. At great depths within Jupiter, the pressure is so great that the hydrogen atoms are broken up and the electrons
are freed so that the resulting atoms consist of bare protons. This produces a state in which the hydrogen becomes metallic.
Colorful latitudinal bands, atmospheric clouds and storms illustrate Jupiter's dynamic weather systems. The cloud patterns
change within hours or days. The Great Red Spot is a complex storm moving in a counter-clockwise direction. At the outer edge, material appears to rotate in four to six
days; near the center, motions are small and nearly random in direction. An array of other smaller storms and eddies can be
found through out the banded clouds.
Auroral emissions, similar to Earth's northern lights, were observed in the polar regions of Jupiter. The auroral emissions appear to be related to material from Io that spirals along magnetic field lines to fall into Jupiter's atmosphere. Cloud-top lightning bolts, similar to superbolts
in Earth's high atmosphere, were also observed.
Unlike Saturn's intricate and complex ring patterns, Jupiter has a simple ring system that is composed of an inner halo,
a main ring and a Gossamer ring. To the Voyager spacecraft, the Gossamer ring appeared to be a single ring, but Galileo imagery
provided the unexpected discovery that Gossamer is really two rings. One ring is embedded within the other. The rings are
very tenuous and are composed of dust particles kicked up as interplanetary meteoroids smash into Jupiter's four small inner
moons Metis, Adrastea, Thebe, and Amalthea. Many of the particles are microscopic in size.
The innermost halo ring is toroidal in shape and extends radially from about 92,000 kilometers (57,000 miles) to about
122,500 kilometers (76,000 miles) from Jupiter's center. It is formed as fine particles of dust from the main ring's inner
boundary 'bloom' outward as they fall toward the planet. The main and brightest ring extends from the halo boundary out to
about 128,940 kilometers (80,000 miles) or just inside the orbit of Adrastea. Close to the orbit of Metis, the main ring's
The two faint Gossamer rings are fairly uniform in nature. The innermost Amalthea Gossamer ring extends from the orbit
of Adrastea out to the orbit of Amalthea at 181,000 kilometers (112,000 miles) from Jupiter's center. The fainter Thebe Gossamer
ring extends from Amalthea's orbit out to about Thebe's orbit at 221,000 kilometers (136,000 miles).
Jupiter's rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet's magnetic
field. These particles and fields comprise the jovian magnetosphere or magnetic environment, which extends 3 to 7 million kilometers (1.9 to 4.3 million miles) toward the Sun, and stretches
in a windsock shape at least as far as Saturn's orbit - a distance of 750 million kilometers (466 million miles).
|Mass (Earth = 1)
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|Mean distance from the Sun (km)
|Mean distance from the Sun (Earth = 1)
|Rotational period (days)
|Orbital period (days)
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|Tilt of axis (degrees)
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This image was taken by NASA's Hubble Space Telescope on February 13, 1995. The image provides a detailed look at a unique
cluster of three white oval-shaped storms that lie southwest (below and to the left) of Jupiter's Great Red Spot. The appearance
of the clouds, in this image, is considerably different from their appearance only seven months earlier. These features are
moving closer together as the Great Red Spot is carried westward by the prevailing winds while the white ovals are swept eastward.
The outer two of the white storms formed in the late 1930s. In the centers of these cloud systems the air is rising, carrying
fresh ammonia gas upward. New, white ice crystals form when the upwelling gas freezes as it reaches the chilly cloud top level
where temperatures are -130°C (-200°F). The intervening white storm center, the ropy structure to the left of the ovals, and
the small brown spot have formed in low pressure cells. The white clouds sit above locations where gas is descending to lower,
Cassini Jupiter Portrait
This true color mosaic of Jupiter was constructed from images taken by the Cassini spacecraft on December 29, 2000, during
its closest approach to the giant planet at a distance of approximately 10 million kilometers (6.2 million miles).
It is the most detailed global color portrait of Jupiter ever produced; the smallest visible features are approximately
60 kilometers (37 miles) across. The mosaic is composed of 27 images: nine images were required to cover the entire planet
in a tic-tac-toe pattern, and each of those locations was imaged in red, green, and blue to provide true color. Although Cassini's
camera can see more colors than humans can, Jupiter's colors in this new view look very close to the way the human eye would
Everything visible on the planet is a cloud. The parallel reddish-brown and white bands, the white ovals, and the large
Great Red Spot persist over many years despite the intense turbulence visible in the atmosphere. The most energetic features
are the small, bright clouds to the left of the Great Red Spot and in similar locations in the northern half of the planet.
These clouds grow and disappear over a few days and generate lightning. Streaks form as clouds are sheared apart by Jupiter's
intense jet streams that run parallel to the colored bands. The prominent dark band in the northern half of the planet is
the location of Jupiter's fastest jet stream, with eastward winds of 480 kilometers (300 miles) per hour. Jupiter's diameter
is eleven times that of Earth, so the smallest storms on this mosaic are comparable in size to the largest hurricanes on Earth.
Unlike Earth, where only water condenses to form clouds, Jupiter's clouds are made of ammonia, hydrogen sulfide, and water.
The updrafts and downdrafts bring different mixtures of these substances up from below, leading to clouds at different heights.
The brown and orange colors may be due to trace chemicals dredged up from deeper levels of the atmosphere, or they may be
byproducts of chemical reactions driven by ultraviolet light from the Sun. Bluish areas, such as the small features just north
and south of the equator, are areas of reduced cloud cover, where one can see deeper. (Courtesy NASA/JPL/Space Science
The Interior of Jupiter
This picture illustrates the internal structure of Jupiter. The outer layer is primarily composed of molecular hydrogen.
At greater depths the hydrogen starts resembling a liquid. At 10,000 kilometers below Jupiter's cloud top liquid hydrogen
reaches a pressure of 1,000,000 bar with a temperature of 6,000° K. At this state hydrogen changes into a phase of liquid
metallic hydrogen. In this state, the hydrogen atoms break down yeilding ionized protons and electrons similar to the Sun's
interior. Below this is a layer dominated by ice where "ice" denotes a soupy liquid mixture of water, methane, and ammonia
under high temperatures and pressures. Finally at the center is a rocky or rocky-ice core of up to 10 Earth masses. (Copyright
Calvin J. Hamilton)
Thin Crescent Image of Jupiter
This thin crescent picture of Jupiter was created from a photomosaic of images Galileo took on its C9 orbit. It is made
from Near Infrared and Violet images, with an artificial green image produced from the other two. (Courtesy of Ted Stryk)
Nordic Optical Telescope
This image of Jupiter was taken with the 2.6 meter Nordic Optical Telescope, located at La Palma, Canary Islands. It
is a good example of the best imagery that can be obtained from earth based telescopes. (c) Nordic Optical Telescope Scientific
Jupiter with Satellites Io and Europa
Voyager 1 took this photo of Jupiter and two of its satellites (Io, left, and Europa, right) on Feb. 13, 1979. In this view, Io is about 350,000 kilometers (220,000 miles) above Jupiter's Great Red Spot, while
Europa is about 600,000 kilometers (373,000 miles) above Jupiter's clouds. Jupiter is about 20 million kilometers (12.4 million
miles) from the spacecraft at the time of this photo. There is evidence of circular motion in Jupiter's atmosphere. While
the dominant large scale motions are west-to-east, small scale movement includes eddy like circulation within and between
the bands. (Courtesy NASA/JPL)
Satellite Footprints Seen in Jupiter Aurora
In this Hubble Space Telescope picture, a curtain of glowing gas is wrapped around Jupiter's north pole like a lasso.
This curtain of light, called an aurora, is produced when high-energy electrons race along the planet's magnetic field and
into the upper atmosphere where they excite atmospheric gases, causing them to glow. The aurora resembles the same phenomenon
that crowns Earth's polar regions. But this Hubble image, taken in ultraviolet light, also shows the glowing "footprints"
of three of Jupiter's largest moons: Io, Ganymede, and Europa.
Courtesy of NASA/ESA, John Clarke (University of Michigan)
This image taken by the ion and neutral mass spectrometer instrument on NASA's Cassini spacecraft makes the huge magnetosphere
surrounding Jupiter visible in a way no instrument on any previous spacecraft has been able to do. The magnetosphere is a
bubble of charged particles trapped within the magnetic environment of the planet. A magnetic field is sketched over the image
to place the energetic neutral atom emissions in perspective. This sketch extends in the horizontal plane to a width 30 times
the radius of Jupiter. Also shown for scale and location are the disk of Jupiter (black circle) and the approximate position
(yellow circles) of the doughnut-shaped torus created from material spewed out by volcanoes on Io.
Some of the fast-moving ions within the magnetosphere pick up electrons to become neutral atoms, and once they become neutral,
they can escape Jupiter's magnetic field, flying out from the magnetosphere at speeds of thousands of kilometers, or miles,
These HST images, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission
rings are linked to the planet's volcanic moon, Io. The top panel pinpoints the effects of emissions from Io. The image on the left, shows how Io and Jupiter are linked by
an invisible electrical current of charged particles called a flux tube. The particles, ejected from Io by volcanic
eruptions, flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles.
The top-right image shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the
auroral spots called "footprints." The spots are created when the particles in Io's "flux tube" reach Jupiter's upper atmosphere
and interact with hydrogen gas, making it fluoresce.
The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure
as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to
15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning
to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission
inside the main auroral oval.
Credits: John T. Clarke and Gilda E. Ballester (University of Michigan), John Trauger and Robin Evans (Jet Propulsion
Laboratory), and NASA.
The Great Red Spot
This dramatic view of Jupiter's Great Red Spot and its surroundings was obtained by Voyager 1 on Feb. 25, 1979, when
the spacecraft was 9.2 million kilometers (5.7 million miles) from Jupiter. Cloud details as small as 160 kilometers (100
miles) across can be seen here. The colorful, wavy cloud pattern to the left of the Red Spot is a region of extraordinarily
complex and variable wave motion. (Courtesy NASA)
False Color of Jupiter's Great Red Spot
This image is a false color representation of Jupiter's Great Red Spot taken with Galileo's imaging system through three
different near-infrared filters. This is a mosaic of eighteen images (6 in each filter) that were taken over a period of 6
minutes on June 26, 1996. The Great Red Spot appears pink and the surrounding region blue because of the particular color
coding used in this representation. The red channel is the reflectance of Jupiter at a wavelength where methane strongly absorbs
(889nm). Because of this absorption, only high clouds can reflect sunlight in this wavelength. The green channel is the reflectance
in a wavelength where methane absorbs, but less strongly (727nm). Lower clouds can reflect sunlight in this wavelength. Finally,
the blue channel is the reflectance in a wavelength where there are essentially no absorbers in the Jovian atmosphere (756nm)
and one sees light reflected from the deepest clouds. Thus, the color of a cloud in this image indicates its height, with
red or white being highest and blue or black being lowest. This image shows the Great Red Spot to be relatively high, as are
some smaller clouds to the northeast and northwest that are surprisingly like towering thunderstorms found on earth. The deepest
clouds are in the collar surrounding the Great Red Spot, and also just to the northwest of the high (bright) cloud in the
northwest corner of the image. Preliminary modelling shows these cloud heights to range about 50km in altitude. (Courtesy
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.
(Copyright Calvin J. Hamilton)
The Jovian System
The best of the Jupiter system is pictured in this collage of images acquired by the Voyager and Galileo spacecraft.
Jupiter is the largest planet in our solar system. The four largest moons of Jupiter are known as the Galilean moons and are
named Callisto, Ganymede, Europa, and Io. Inside the orbits of the Galilean moons are Thebe, Amalthea, Adrastea, and Metis. At the lower right is shown the Valhalla region of Callisto. Ganymede is toward the bottom middle. Europa is a little above
and to the right of Ganymede. Io is the top, left-most moon. Between Io and Jupiter are four little moons. The top-most little
moon is Amalthea. Below and to the right of Amalthea are Metis and Adrastea. To the left of Adrastea is Thebe. (Copyright
Calvin J. Hamilton)
Moons of Jupiter
This image shows to scale Jupiter's moons Amalthea, Io, Europa, Ganymede, and Callisto. (Copyright Calvin J. Hamilton)
||October 10, 1846|
||130.267° (to the ecliptic)|
157.340° (to Neptune's equator)
130.063° (to Neptune's orbit)
||2706.8±1.8 km |
||5 d, 21 h, 2 min, 28s|