dipper@utastro.UUCP (Debbie Byrd) (03/05/85)
NASA's Voyager 1 spacecraft was the first to get a good look at Jupiter and its moons. More -- in just a few moments. March 5 The Voyager Encounter with Jupiter Just six years ago, on this date in 1979, NASA's Voyager 1 encountered the planet Jupiter. It was the third spacecraft ever to visit Jupiter -- but the first to see it well. Voyager 1 revealed so many surprises about Jupiter and its moons that one mission scientist said, "Our sense of novelty couldn't have been greater if we'd explored a different solar system!" Before Voyager, Jupiter was seen from Earth as a fuzzy ball crossed with red and tan cloud bands. We'd also seen the Red Spot -- a great storm on Jupiter -- as wide as two planet Earths. But Voyager revealed much more -- chaotic structure within the cloud bands -- horizontal currents and oval-shaped storms raging in the Jovian atmosphere. Voyager also found a ring around Jupiter -- smaller and far more tenuous than Saturn's glorious rings -- but still a major discovery. But the biggest surprise wasn't Jupiter -- it was Jupiter's moons. The disks of the four Galilean satellites are barely visible through powerful earthbound telescopes. It took a spacecraft to see these moons as they are -- new worlds to explore. Like Earth and maybe Venus, Jupiter's moon Io has active volcanos. Europa has a smooth surface layer of ice -- with a possible liquid ocean underneath. Ganymede, the largest moon, is half-cratered -- but half-scarred by the shifting of its surface crust. Meanwhile, the surface of Callisto is all craters -- bearing a record unchanged since the early days of the solar system -- to be read by explorers from the blue and green planet Earth. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin