Jupiter and Its Four Largest Moons Composite

Jupiter hangs in the upper right of a black field, its disc banded in cream, rust and tan. A large oval storm sits in the southern half, and smaller pale spots break up the stripes. The edge of the planet fades softly into darkness. Four moons are placed below and to the left in a loose diagonal. The smallest is a tiny orange-yellow globe at far left. Next to it is a paler, cream-coloured moon with faint mottling. Below that, a darker brown moon shows bright streaks and patches. At lower right, a much larger dark globe is cut off by the frame, its surface covered in small bright rings and speckles.

This is a montage, not a single exposure. Separate images from the Voyager spacecraft were arranged together, so the sizes and spacing are not to scale. The four moons are the large Galilean satellites: Io, Europa, Ganymede and Callisto. Galileo observed them in 1610. Io is volcanically active, Europa has an icy shell over a likely ocean, Ganymede is the largest moon in the solar system, and Callisto has one of the most heavily cratered surfaces known. The deep black background and off-centre layout suit a widescreen desktop monitor, where the planet and moons have room to sit apart.

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