Ringmakers of Saturn PDF - Patrick Crusade

SATURN'S RINGS EXPLAINED
incomplete A ring in a polar view of Saturn's northern hemisphere.
Earth profiles are introduced to provide a familiar reference measure.
Line-of-sight is perpendicular to the ring plane so that all rings appear
in true relative proportion. The length of the ring-segment chord is
greater than Saturn's diameter. This fact is illustrated by projection of
parallel dotted lines from Saturn to the chord. These dotted lines
intersect the ring chord within the cut-off segment of the A ring. The
Enke division, placed at 2/5 the A-ring width from the outer edge, can
be seen to intersect the chord at nearly the same points as the projected
dotted lines. The distance subtended by the entire chord is equivalent
to slightly over 10 earth diameters. Only about 6 earth diameters
comprise the radial distance from Saturn's surface to the A-ring outer
edge. Other distances also can be compared. For example, the radial
span from the inner edge of the A ring to the outer edge of the Enke
division is about one earth diameter. Span of the Enke division is
expressed by a mere line width inasmuch as this gap is only about 200
km (125 mi) across. Radial span of the Cassini division is about 0.3
earth diameter. As before, Saturn's diameter is 120,660 km (74,980 mi).
Circled numerals cross-reference the corresponding numerals shown in
Plate 3.
When the photograph of Plate 3 is enlarged in the vicinity of numeral
(1), the information of Plate 5 is obtained. In Plate 5, efflux from along
Plate 5: Efflux from along the length of a slender body, exhausting at both ends, generates
the A-ring.
17