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 16 satellites, four of which - Callisto, Europa, Ganymede and Io - were observed by Galileo as long ago as 1610. 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 single ring that is almost uniform in its structure. It is probably composed of dust particles less than 10 microns in diameter -- about the size of cigarette smoke particles. It extends to an outer edge of about 129,000 kilometers (80,161 miles) from the center of the planet and inward to about 30,000 kilometers (18,642 miles). The origin of the ring is probably from micrometeorite bombardment of the tiny moons orbiting within the ring.
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 (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 (hours) ............................. 9.841 Orbital period (years) .............................. 11.8623 Mean orbital velocity (km/sec) ........................ 13.07 Orbital eccentricity ................................. 0.0483 Tilt of axis ........................................... 3.13° Orbital inclination ................................... 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 ............................... -121°C Atmospheric pressure (bars) ............................. 0.7 Atmospheric composition Hydrogen ............................................ 90% Helium .............................................. 10%
Jupiter
(GIF, 265K;
caption)
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, warmer regions.
Jupiter
(GIF, 265K)
This image was taken by the Wide Field/Planetary Camera of the Hubble
Telescope. It is a true color composite of the full disk of Jupiter. All
features in this image are cloud formations in the Jovian atmosphere,
which contain small crystals of frozen ammonia and traces of colorful
compounds of carbon, sulfur and phosphorous. This photograph was
taken on May 28, 1991. (Courtesy NASA/JPL)
Nordic Optical Telescope
(GIF, 56K)
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 Association (NOTSA).
Jupiter and Moons
(GIF, 114K)
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)
The Great Red Spot
(GIF, 144K;
GIF, 413K)
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/JPL).
Ring of Jupiter
(GIF, 13K)
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.
(Credit: Calvin J. Hamilton, DOD)
Equator of Jupiter
(GIF, 390K)
This image shows the entire equatorial region of Jupiter. It was created
from a mosaic of several images. The Great Red Spot is
toward the left of the image.
(Credit: Calvin J. Hamilton, DOD/NASA)
Moons of Jupiter
(GIF, 261K;
TIF, 2M)
This image shows to scale Jupiter's moons
Amalthea, Io,
Europa, Ganymede,
and Callisto.
(Credit: Calvin J. Hamilton, DOD)
Hubble Photo Gallery of the Galilean Satellites
(GIF, 92K;
caption)
This is a Hubble Space Telescope family portrait of the four
largest moons of Jupiter, first observed by the Italian scientist
Galileo Galilei
nearly four centuries ago. Located approximately one-half
billion miles away, the moons are so small that, in visible light, they
appear as fuzzy disks in the largest ground-based telescopes. Hubble
can resolve surface details seen previously only by the Voyager
spacecraft in the early 1980's.
Hubble has charted new volcanic activity on Io's active surface, found a faint oxygen atmosphere on the moon Europa, and identified ozone on the surface of Ganymede. Hubble ultraviolet observations of Callisto show the presence of fresh ice on the surface that may indicate impacts from micrometeorites and charged particles from Jupiter's magnetosphere. (Credit: STScI/NASA)
Name Distance* Width Thickness Mass Albedo ---------------------------------------------------------------- Halo 100,000 km 22,800 km 20,000 km ? 0.05 Main 122,800 km 6,400 km < 30 km 1 x 10^13 kg 0.05 Gossamer 129,200 km 850,000 km ? ? 0.05
*The distance is measured from the planet center to the start of the ring.
Sixteen moons have been discovered orbiting around Jupiter. Most of them are relatively small and seem to have been more likely captured than to have been formed in orbit around Jupiter. Four of the largest moons, Io, Europa, Ganymede and Callisto, are believed to have accreted as part of the process by which Jupiter itself formed. The following table summarizes the radius, mass, distance from the planet center, discoverer and the date of discovery of each of the moons of Jupiter:
Radius Mass Distance Moon # (km) (kg) (km) Discoverer Date ------------------------------------------------------------------- Metis XVI 20 9.56e+16 127,969 S. Synnott 1979 Adrastea XV 12.5x10x7.5 1.91e+16 128,971 Jewitt-Danielson 1979 Amalthea V 135x84x75 7.17e+18 181,300 E. Barnard 1892 Thebe XIV 55x45 7.77e+17 221,895 S. Synnott 1979 Io I 1,815 8.94e+22 421,600 Marius-Galileo 1610 Europa II 1,569 4.80e+22 670,900 Marius-Galileo 1610 Ganymede III 2,631 1.48e+23 1,070,000 Marius-Galileo 1610 Callisto IV 2,400 1.08e+23 1,883,000 Marius-Galileo 1610 Leda XIII 8 5.68e+15 11,094,000 C. Kowal 1974 Himalia VI 93 9.56e+18 11,480,000 C. Perrine 1904 Lysithea X 18 7.77e+16 11,720,000 S. Nicholson 1938 Elara VII 38 7.77e+17 11,737,000 C. Perrine 1905 Ananke XII 15 3.82e+16 21,200,000 S. Nicholson 1951 Carme XI 20 9.56e+16 22,600,000 S. Nicholson 1938 Pasiphae VIII 25 1.91e+17 23,500,000 P. Melotte 1908 Sinope IX 18 7.77e+16 23,700,000 S. Nicholson 1914
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