Jupiter is an ancient planet and scientists believe it looks the way it did when the universe was formed. They had thought Jupiter was the largest planet up until last week, when evidence was found of two larger planets orbiting stars similar to the sun. Changes in the theory of Jupiter's origin will affect scientists' theories about those planets, as well. Galileo, launched in 1989 aboard space shuttle Atlantis, will orbit Jupiter and eight of its 16 moons for two years. It will pass by Jupiter's moon Ganymede on June 27.
Scientists plan to continue to study the data for the next several years.
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