[Illustration: 11/12/80 717,000 km (444,000 mi)
The rings of Saturn have amazed and intrigued astronomers for over
300 years. Now that we have seen them up close, they are even more
astonishing. Although they stretch over 65,000 kilometers (40,000
miles), they may be only a few kilometers thick. The ring
particles—from a few microns to a meter (three feet) in size—have
been described as icy snowballs or ice-covered rock. Voyager
scientists continue to pore over their data, searching for answers
to the puzzles of the rings. The rings were named in order of their
discovery, so the labels do not indicate their relative positions.
From the planet outward, they are known as D, C, B, A, F, and E.]
[Illustration: 10/25/80 24 million km (15 million mi)
Extraordinarily complex structure is seen across the entire span of
Saturn’s ring system. The sequence (taken approximately every 15
minutes as Voyager 1 approached Saturn) proceeds from top to bottom
in each column and shows radial “spokes” rotating within the B-Ring.
The spokes may be caused by a combination of magnetic and
electrostatic forces.]
[Illustration: 11/6/80 8 million km (5 million mi)
Over 95 individual concentric features can he counted; the final
count in higher resolution images may be anywhere from 500 to 1000
separate rings. A few of the ringlets shown in this
computer-assembled mosaic are not concentric circles but are instead
elliptical. Ring particles are probably ice or ice covered rock.]
[Illustration: The classic features of the rings are illustrated in
the diagram.]
D-RING
C-RING
B-RING
“SPOKE”
CASSINI DIVISION
ENCKE DIVISION
A-RING
F-RING
[Illustration: 11/8/80 6 million km (3.7 million mi)
The Cassini Division is filled with numerous ringlets. Discovered by
Cassini in 1675, this area between the A- and B-Rings had long been
thought devoid of material. The Voyager observation of well-defined
rings within the Cassini Division was an unexpected discovery.]
[Illustration: 11/12/80 740,000 km (460,000 mi)
Saturn’s ring system, viewed from below, appears dramatically
different from its appearance on the sunlit side. This
computer-processed image shows the F-Ring circling outside the
A-Ring, the A-Ring with its Encke Division, the multiple ringlets in
the Cassini Division, and the optically thick B-Ring, seen here in
magenta hues (the coloration is an artifact of processing and is not
real). The B-Ring appears dark from below the ring plane because it
is dense enough to reflect most of the sunlight, causing it to
appear very bright when seen from the sunward side. The opaline
brightness of the Cassini Division here indicates a great deal of
sunlight being scattered through this region. The Encke Division may
really be empty, since it appears dark from both above and below.]
[Illustration: 11/12/80 720,000 km (450,000 mi)
Outbound and above the ring plane, Voyager 1 gave us this view of
Saturn’s rings eight hours after its closest approach to the planet.
The unique lighting accentuates the many hundreds of bright and dark
ringlets comprising the ring system. The C-Ring (dark gray area)
seems to blend into the brighter B-Ring as the concentric features
radiate out from the planet. The dark spoke-like features seen in
images taken during the approach to Saturn now appear as bright
streaks, indicating that they may be composed of small particles.]
[Illustration: 11/12/80 750,000 km (470,000 mi)
Two narrow, braided rings in the F-Ring are evident in this view, as
well as a broader, very diffuse component about 35 kilometers (20
miles) across. A totally unexpected discovery, the braided rings
trace distinctly separate orbits intertwining each other. The
“knots” may be local clumps of ring material or tiny moons. It is
difficult to explain this complicated structure using only the
gravitational forces known to be affecting the particles of this
ring. It is possible that additional, electrostatic forces may also
influence these particles.]
[Illustration: 11/8/80 7 million km (4.3 million mi)
Brightness variations in the F-Ring may be due to clumping in the
ring material. The features are seen at the top and again near the
left edge of the ring in this image. The “gap” in the ring (left
center) is not real but is the location of a reseau mark on the
camera’s vidicon tube. These bright features in the F-Ring appear to
move at the orbital rate of the ring particles and may be larger
bodies or thicknesses in the rings. Saturn’s thirteenth and
fourteenth satellites, which orbit on either side of the F-Ring, may
act like “sheepdogs,” herding the F-Ring particles between them.
Less than 100 kilometers (60 miles) wide, the F-Ring is located
outside of the A-Ring. Satellite 14, discovered by Voyager 1, is
seen just inside the F-Ring.]