The planet had 39 known moons at the time of this image and a slight ring of smoke-sized particles and dust. The planet contains 71% of the planetary matter in the solar system and so its huge gravity pulls every object toward it. In fact, most of its moons were captured rather than forming with Jupiter. Scientists watched in awe as comet Shoemaker-Levy 9 broke up and smashed into Jupiter making explosions the size of the Earth.
New Moons for Jupiter
Scientists keep finding more moons orbiting Jupiter. In May of 2002, Scott S. Sheppard and David C. Jewitt of the University of Hawaii announced the discovery of 11 new moons around the planet. As of March, 2003, Jupiter had 52 confirmed satellites. These newest moons are all no more than 2 to 4 kilometers across (if their surfaces are very dark), they all have retrograde (backward) orbits, and take somewhere between 557 and 773 days to orbit. These latest moonlets were announced by the International Astronomical Union (IAU) on Circular number 8089. In April, 2003, 8 more moons were confirmed for a total of 60 moons with the possibility of more as the search continues.
The box below shows how the four main satellites or moons (Io, Europa, Ganymede and Callisto) of Jupiter would look in realtime (right now). If you have binoculars or a telescope you can see the moons as tiny points of light. If you look the next night you can see for youself that they move.
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The author, Gary Nugent, describes how to use the applet:
"The distances of the satellites from Jupiter are in proportion to that of the real Jovian system.
"The left-to-right order of the satellites are given by the satellite names displayed in the lower left box. Satellite names in red indicate that the satellite is being occulted (behind) by Jupiter. Satellite names in yellow represent transiting satellites.
"When you click on the image of Jupiter or any of the satellite images you will be taken to the appropriate page at The Nine Planets site. Clicking on the '?' displays a brief description of the applet and clicking on the globe (lower right) brings you to my home page."
Jupiter's main ring system is formed by dust kicked up as interplanetary meteoroids smash into the giant planet's four small inner moons Almathea, Thebe, Adrastea and Metis. The ring system begins about 92,000 kilometers (55,000 miles) from Jupiter's center and extends to about 250,000 kilometers (150,000 miles) from the planet. NASA's Voyager 2 detected an uneven dust ring around Jupiter in 1979. One Voyager image seemed to indicate a third, faint outer ring. The Galileo spacecraft found a flattened main ring and an inner, cloud-like ring, called the halo, both composed of small, dark particles, and a third ring known as the Gossamer Ring. The third ring is actually two very thin rings made up of debris from Amalthea and Thebe. Unlike Saturn's rings, there are no signs of ice in Jupiter's rings.
Click on image for a detail view of this NASA/JPL diagram.
Recently, scientists have found evidence for a new ring of dust in a backward orbit around Jupiter, based on computer simulations and data collected by a dust detector aboard the Galileo spacecraft. A faint, doughnut-shaped ring of interplanetary and interstellar dust some 1,126,000 kilometers in diameter (about 700,000 miles) appears to be orbiting the giant planet. The reason for the backward orbit of the tiny particles is not known.
Gravity and You
Your weight on Earth is determined by your mass and Earth's mass. Would you weigh more or less on Jupiter?
Why are the planets named for Roman gods? What is the story or myth about their names? Click image or here for Planet Myths and Lore.
Are There Planets Like Jupiter Around Other Stars?
|Quick Facts about Jupiter|
|Mass||1.900 x 1027 kg|
|Volume||1.377 x 1015 km3|
|Temperature Range||-163° C to >-121° C|
|Atmosphere||Hydrogen, Helium, Methane|
|Winds||Up to 150 m/s|
|Average Distance from Sun||778,330,000 km|
|Orbital Period||11 Years, 315 Days, 1.1 Hours|
|Rotation||0 Days, 9.925 Hours|
|Composition||Hydrogen and Helium|
|Magnetic Field||Extends 1,600,000 km|
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At right is an artist's view of Galileo orbiting Jupiter.
Click to go to the Galileo Mission website.
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