File:Jupiter - Voyager 1 (46027301945).png

Voyager 1 mosaic of Jupter taken on February 22, 1979 from a distance of ~12.7 million km. The Galilean moons Europa (left), Ganymede (center) and Io are visible. Io's shadow is just beginning to track across Jupiter's cloud-tops at right. IN addition to the major moons, the 250 x 140 x 125 ring moon Amalthea and its eclipse shadow are also visible against Jupiter's cloudtops. They are located nearly along the equator; Amalthea is located almost dead center within a large Equatorial Zone plume, while its shadow is visible on a dark cloud band at the equator.

The mosaic captures an aspect of the Galilean moons' orbital dynamics. Io, Europa and Ganymede are locked in a 1:2:4 orbital resonance. The moons occasionally form a straight line through Jupiter's center of mass. However, this alignment only occurs when Io and Ganymede are on one side of the planet, while Europa is on the other. This resonant activity is responsible for the tectonic activity on all three moons. The high degree of tidal stretching experienced by Io has fuels its intense volcanic activity, while on Europa it is responsible for the relatively craterless ice shell. The tectonic activity is less intense on Ganymede, but has still created large stable icy plates that slowly move around and rework large portions of the moon's terrain.

This mosaic was acquired as a 3x3 three-color imaging sequence between 4:08 and 4:45 UT. Because Jupiter and its moons moved significantly over the imaging sequence, this is an approximation of Voyager's view. Jupiter's cloud features are aligned as they would have appeared at 4:25 UT. In addition, Io's shadow (left) did not appear on Jupiter's cloudtops until after Ganymede finished transiting. Finally, at the beginning of this imaging sequence, Europa was located just below Jupiter's horizon until late in the imaging sequence.