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Side-Lights on Astronomy and Kindred Fields of Popular Science by Simon Newcomb
page 98 of 331 (29%)
probably a hot mass of vapor hundreds of miles deep, thrown up
from the heated interior. The belts are probably cloudlike forms
in this vaporous mass. Certain it is that they are continually
changing, so that the planet seldom looks exactly the same on two
successive evenings. The rotation of the planet can be very well
seen by an hour's watching. In two hours an object at the centre
of the disk will move off to near the margin.

The satellites of this planet, in their ever-varying phases, are
objects of perennial interest. Their eclipses may be observed with
a very small telescope, if one knows when to look for them. To do
this successfully, and without waste of time, it is necessary to
have an astronomical ephemeris for the year. All the observable
phenomena are there predicted for the convenience of observers.
Perhaps the most curious observation to be made is that of the
shadow of the satellite crossing the disk of Jupiter. The writer
has seen this perfectly with a six-inch telescope, and a much
smaller one would probably show it well. With a telescope of this
size, or a little larger, the satellites can be seen between us
and Jupiter. Sometimes they appear a little brighter than the
planet, and sometimes a little fainter.

Of the remaining large planets, Mercury, the inner one, and Uranus
and Neptune, the two outer ones, are of less interest than the
others to an amateur with a small telescope, because they are more
difficult to see. Mercury can, indeed, be observed with the
smallest instrument, but no physical configurations or changes
have ever been made out upon his surface. The question whether any
such can be observed is still an open one, which can be settled
only by long and careful scrutiny. A small telescope is almost as
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