17. The Planets and Comets which move round the Sun as their center,
constitute the Solar System. Those Planets which are nearer the Sun not
only finish their circuits sooner, but likewise move faster in their
respective Orbits than those which are more remote from him. Their
motions are all performed from west to east, in Orbits nearly circular.
Their names, distances, bulks, and periodical revolutions, are as
follows.
[Sidenote: The Sun.]
18. The SUN ☉, an immense globe of fire, is placed near the common
center, or rather in the lower[2] focus, of the Orbits of all the
Planets and Comets[3]; and turns round his axis in 25 days 6 hours, as
is evident by the motion of spots seen on his surface. His diameter is
computed to be 763,000 miles; and, by the various attractions of the
circumvolving Planets, he is agitated by a small motion round the center
of gravity of the System. All the Planets, as seen from him, move the
same way, and according to the order of Signs in the graduated Circle ♈
♉ ♎ ♋ &c. which represents the great Ecliptic in the Heavens: but, as
seen from any one Planet, the rest appear sometimes to go backward,
sometimes forward, and sometimes to stand still; not in circles nor
ellipses, but in[4] looped curves which never return into themselves.
The Comets come from all parts of the Heavens, and move in all sorts of
directions.
[Sidenote: PLATE I. Fig. I. The Sun.