Looking beyond matters of technology and the environment, the historian may cite the latter part of the twentieth century as a time of explosive exploration, comparable to the 15th and 16th century exploration of the Earth’s oceans and the distant lands that bounded them. In a sense, exploration—whether it is physical or intellectual—provides its own rewards. The United States has always been a nation that moves forward, pushing back the frontiers of the West, pushing back the frontiers of social and economic development, and now pushing back the frontiers of space. It is arguable that this spirit of exploration is indispensable to a vigorous society, and that any society that ceases to explore, to inquire, and to strive is only a few years from decline.
And so the historian may recall the early days of lunar exploration, the Apollo project, the landing of unmanned Viking spacecraft on Mars, and the encounters of Voyager spacecraft with Jupiter and Saturn as the first steps in a sustained program of space exploration—a program that is profoundly changing man’s perspective of himself, of the Earth, and of the larger cosmos beyond.
Thomas A. Mutch, Associate Administrator for Space Science National Aeronautics and Space Administration
Images of Jupiter and Its Satellites
The date of each photograph and the distance of the spacecraft from the planet or satellite are included with each picture.
2/5/79 28.4 million km (17.6 million mi)
Jupiter is the largest planet in our solar system, with a diameter 11 times that of Earth. Jupiter rotates very quickly, making one full rotation in just under ten hours. Composed primarily of hydrogen and helium, Jupiter’s colorfully banded atmosphere displays complex patterns highlighted by the Great Red Spot, a large, circulating atmospheric disturbance. Three of Jupiter’s 13 known satellites are also visible in this Voyager 1 photograph. The innermost large satellite, Io, can be seen in front of Jupiter and is distinguished by its bright, orange surface. To the right of Jupiter is Europa, also very bright but with fainter surface markings. Callisto is barely visible beneath Jupiter. These satellites orbit Jupiter in the equatorial plane and appear in their present position because Voyager is above the plane.
Jupiter’s atmosphere is undergoing constant change, presenting an ever-shifting face to observers. The Great Red Spot has undergone three major periods of activity in the last 15 years. These images of Jupiter, taken by Voyager 1 (top) and Voyager 2 (bottom) almost four months apart, show that cloud movement in the Jovian atmosphere is not uniform because wind speeds vary at different latitudes. For example, the white ovals which appear below the Great Red Spot dramatically shifted between January and May, the time interval between these two pictures. The bright “tongue” extending upward from the Great Red Spot interacted with a thin, bright cloud above it that had traveled twice around Jupiter in four months. Eddy patterns to the left of the Great Red Spot, which have been observed since 1975, appear to be breaking up.
