could be seen with a good opera-glass. So also
might Titan.
Transits, eclipses, and occulations of Saturn's satellites can only be
seen when the ring is turned nearly edgewise towards the earth. For the
orbits of the seven inner satellites lying nearly in the plane of the
rings would (if visible throughout their extent) then only appear as
straight lines, or as long ellipses cutting the planet's disc.
The belts on Saturn are not very conspicuous. A good 3-1/2-inch is
required (so far as my experience extends) to show them satisfactorily.
The rings when turned edgewise either towards the earth or sun, are not
visible in ordinary telescopes, neither can they be seen when the earth
and sun are on opposite sides of the rings. In powerful telescopes the
rings seem never entirely to disappear.
The shadow of the planet on the rings may be well seen with a good
2-inch telescope, which will also show Ball's division in the rings. The
shadow of the rings on the planet is a somewhat more difficult feature.
The shadow of the planet on the rings is best seen when the rings are
well open and the planet is in or near quadrature. It is to be looked
for to the left of the ball (in an inverting telescope) at quadrature
preceding opposition, and to the right at quadrature following
opposition. Saturn is more likely to be studied at the latter than at
the former quadrature, as in quadrature preceding opposition he is a
morning star. The shadow of the rings on the planet is best seen when
the rings are but moderately open, and Saturn is in or near quadrature.
When the shadow lies outside the rings it is best seen, as the dark ring
takes off from the sharpness of the contrast when the shadow lies within
the ring. It would take more space than I can spare here to show how it
is to be determined (independently) whether the shadow lies within or
without the ring. But the 'Nautical Almanac' gives the means of
determining this point. When, in the table for assigning the appearance
of the rings, _l_ is less than _l'_ the shadow lies outside the ring,
when _l_ is greater than _l'_ the shadow lies within the ring.
Uranus is just visible to the naked eye when he is in opposition, and
his place accurately known. But he presents no phenomena of interest. I
have seen him under powers which made his disc nearly equal to that of
the moon, yet could see nothing but a faint bluish disc.
Neptune also is easily found if his place be accurately note
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