Pioneer Saturn image of Saturn and its rings from a distance of 8,400,000 km (August 22, 1979, 10 days before closest approach). Resolution has not yet reached Earth-based quality. Faint banding is visible on the disk of the planet. The silhouette of the rings can be seen in front of the planet. Slightly above this silhouette is the shadow of the rings on the disk. Beyond the disk, structure can be seen in the rings. The rings have a distinctly different appearance in this and subsequent images than in Earth-based pictures because they are illuminated from below rather than from above as we view them from Earth. The A-ring and C-ring are bright, and between them the B-ring is dark. The Cassini Division at the inner edge of the A-ring is also bright, but is blended with the ring at this distance.
Pioneer Saturn image of Saturn and its rings from a distance of 5,500,000 km (August 26, 1979, 6 days before closest approach). Resolution of features is beginning to be approximately equal to that of Earth-based pictures. Belts on the planet are becoming more distinct, and considerable structure can be seen in the rings. The small blue spot at the bottom of the planet is due to incomplete data and will be corrected by further processing. A notch appears at the top left of the planet, which may be a data transmission problem or the shadow of one of Saturn’s moons.
Pioneer Saturn image of Saturn and its rings from a distance of 2,800,000 km (August 29, 1979, 72 hours before closest approach). The Cassini Division at the inner edge of the A-ring is clearly resolved and is bright. The A-ring is dark outside the Cassini Division because it has more particulate matter there. Polar belts are becoming more visible on the face of the planet. Irregularities that appear in the ring silhouette and shadow are due to stepping anomalies in the imaging photopolarimeter and will be removed in further processing. The small round image that appears above the planet is the moon Titan.
These pictures of Saturn and its rings were taken by Pioneer Saturn from a distance of 2,500,000 km (August 29, 1979, 58 hours before closest approach). The imaging photopolarimeter gathers data using the red and blue components of the light reflected from Saturn. These two views are from the two color components (upper, blue; lower, red). The banded structure on the planet is particularly evident in the upper image. Because the spacecraft is nearing the planet, the rings are partially outside the field of view of the instrument. The speck of light below the planet is Saturn’s moon Rhea, which is 1450 km in diameter, about one-half the size of Earth’s moon.
This image was produced by combining the two images on the facing page, adding a synthesized green component, and adjusting the intensity of each to obtain an approximation to Saturn’s true color. (The same process was used in all of the Pioneer color images of Saturn shown here.) Although not evident on this reproduction, scientists believe that, from detailed study of both the uncombined and the combined images, they can begin to see evidence of jet streams in Saturn’s upper atmosphere. The slight blue edge is an artifact from the computer-enhancement procedure.