miles! In fact, the sheet of paper in our imaginary model is several
times too thick to represent the true relative thickness of Saturn's
rings.

Several narrow gaps in the rings have been detected from time to time,
but there is only one such gap that is always clearly to be seen, the
one already mentioned, situated about 10,000 miles from the outer edge
and about 1,600 miles in width. Inside of this gap the broadest and
brightest ring appears, having a width of about 16,500 miles. For some
reason this great ring is most brilliant near the gap, and its
brightness gradually falls off toward its inner side. At a distance of
something less than 20,000 miles from the planet--or perhaps it would
be more correct to say above the planet, for the rings hang directly
over Saturn's equator--the broad, bright ring merges into a mysterious
gauzelike object, also in the form of a ring, which extends to within
9,000 or 10,000 miles of the planet's surface, and therefore itself has
a width of say 10,000 miles.

In consequence of the thinness of the rings they completely disappear
from the range of vision of small telescopes when, as occurs once in
every fifteen years, they are seen exactly edgewise from the earth. In a
telescope powerful enough to reveal them when in that situation they
resemble a thin, glowing needle run through the ball of the planet. The
rings will be in this position in 1907, and again in 1922.

The opacity of the rings is proved by the shadow which they cast upon
the ball of the planet. This is particularly manifest at the time when
they are edgewise to the earth, for the sun being situated slightly
above or below the plane of the rings then throws their shadow across
Saturn close to its equator. When they are canted at a considerable