"Study of the outer solar system began almost 400 years ago, in 1610, when Galileo made his first telescopic observations and discovered Jupiter's four larger moons. Later that same year Galileo aimed his telescope at Saturn and was the first to see its rings. Because of the less-than-adequate resolving power of his telescope, he didn't realize what they were (he reported seeing "cup handles") and it wasn't until 45 years later, in 1655, that Dutch astronomer Christiaan Huygens described the true form of the rings. Not until 1781, when Sir William Herschel discovered Uranus, were any planets beyond Saturn known to exist." "Most of the rest of what we know of our outer solar system has been learned in the last 30 years, beginning with the Pioneer and Voyager missions of the 1970s to Jupiter and beyond. And a staggering amount has been learned in those three decades, some of it far more fascinating and complex than had ever been foreseen. Theories of planetary evolution and behavior have been revised again and again in the face of hard data returned by the scientific instruments of solar system exploration missions years in length. In the summer of 1989, Voyager 2 did a flyby of Neptune, the first spacecraft to do so, a full 12 years after it was launched." "The Galileo spacecraft, launched in 1989, was the first outer solar system orbiter, going into orbit around Jupiter in 1995 to begin a two-year intensive study of the planet. Galileo released the first-ever probe into the atmosphere of another planet. The Cassini spacecraft was launched in 1997, spent seven years reaching Saturn, and then went into orbit to begin a multi-year study of the Saturnian system." "On January 14, 2005, Cassini released the Huygens probe, which entered the atmosphere of Titan, Saturn's largest moon, and parachuted to the surface, radioing scientific observations back to Cassini for relay to Earth. Titan's atmosphere resembles that of primordial Earth and scientists feel that much can be learned about our own world's evolution by studying what's happening now on Titan. Cassini and Huygens are the latest spacecraft in an ongoing long-term effort that has become international in scope, exploring the solar system to help understand the past and prepare for the future. Book jacket."--BOOK JACKET