Far far away, beyond the asteroid belt, born 4.6 billion years ago, lies Jupiter, the fifth planet from the sun and the largest in our solar system. There are many interesting facts about this planet, like its very unusual giant red spot. Many spacecraft collected a wealth of information on Jupiter. Even now, researchers are discovering more information on Jupiter.

Giant Red Spot

Jupiter's most famous feature is the giant red spot.  It's really a hurricane generated by tremendous winds traveling at 250 mph. A hurricane on earth would rarely generate winds above 180 mph. The giant red spot is 300 years old and big enough to hold two Earths. What makes the red spot red is a chemical called phosphorus.

Jupiter's Moons

Jupiter has sixteen mysterious moons. Of these moons, the astronomer Galileo discovered four in the year 1610. That's why they're called Galilean moons. They are Io, Europa, Ganymede, and Callisto. These moons are very interesting. Io was thought to have craters, but they turned out to be active volcanoes. Ganymede is Jupiter's largest moon, and Europa probably contains water. The other twelve moons are classified as small moons. They include Metis, Adrastea, Amalthea, Thebe, Leda, Himilia, Lysithea, Elara, Ananke, Carme, Pasiphae, Sinope. These moons are all named after mythological figures.

Spacecraft Sent to Jupiter

The six spacecraft sent to Jupiter were Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Galileo, and Ulysses. They all had a mission to gather images from space. Galileo, launched in 1979 had a mission to measure the amount of water and chemicals in Jupiter's atmosphere. Pioneer 10 was launched in 1972 and flew within 81,000 miles of Jupiter a year later. Pioneer 10 was successful in finding helium and hydrogen in the planet's atmosphere. Pioneer 11 flew within 27,000 miles of Jupiter in 1974 and provided close up pictures of Jupiter's polar regions. This spacecraft even discovered Jupiter's enormous magnetic field.

Voyagers 1 and 2 flew past Jupiter in 1979. These spacecraft transmitted much more information than the other probes. Astronomers used the Voyagers' photos to make the first detailed map of the Galilean moons. Both Voyagers discovered sulfur in the volcanoes of Io.

Ulysses, launched in October 1990, passed by Jupiter two years later. This probe was used to study the polar regions. It gathered data on solar wind. The data showed that solar winds have a greater effect on Jupiter's magnetic than previously thought.

On January 17, 2002, Galileo will make its final flyby of Io when it sweeps within 62,000 miles of it. In 2003, it will slam into Jupiter. Altogether, Galileo collected 14,000 images.

Colonizing Europa

The mystery continues about colonizing Europa. To find this out, astronomers have sent a probe to Europa to take pictures of this moon of Jupiter. From this they know that there is a lot of ice on Europa. The ice formed when water came up from Europa's surface and froze. Scientists think that water is underneath that ice.

Recent observations reveal that Europa has a thin atmosphere made of oxygen. It is likely generated by sunlight hitting the icy surface. This produces water vapor which is split into hydrogen and oxygen. The hydrogen escapes leaving the oxygen. If astronomers find nitrogen, then it will be exciting to know if people can live there.

Jupiter's Surface

What lies beneath the clouds of Jupiter is still a mystery. Most scientists think it's hot. In the 1930's astronomers found that it has no surface. Jupiter's atmosphere is made of hydrogen and helium. It is likely to be an all gas planet.

Rotation of Jupiter

Since Jupiter is the largest planet, you might think Jupiter rotates the slowest of all nine planets. Actually, Jupiter rotates faster than any other planet. In fact, it rotates in less than 10 hours.

Interesting Facts About Jupiter

Bill Arnett. Seds. <http://www.seds.org./nineplanets/nineplanets> Last Visited: December, 2001.

Everything You Need to Know and Beyond! </J0112388> Last Visited: December, 2001.

Space Today, Tomorrow, and Always. </J0112188> Last Visited: December, 2001.

The Detroit News. January 22, 2002.

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