_Of Astronomy in general._
[Sidenote: The general use of Astronomy.]
1. Of all the sciences cultivated by mankind, Astronomy is acknowledged
to be, and undoubtedly is, the most sublime, the most interesting, and
the most useful. For, by knowledge derived from this science, not only
the bulk of the Earth is discovered, the situation and extent of the
countries and kingdoms upon it ascertained, trade and commerce carried
on to the remotest parts of the world, and the various products of
several countries distributed for the health, comfort, and conveniency
of its inhabitants; but our very faculties are enlarged with the
grandeur of the ideas it conveys, our minds exalted above the low
contracted prejudices of the vulgar, and our understandings clearly
convinced, and affected with the conviction, of the existence, wisdom,
power, goodness, and superintendency of the SUPREME BEING! So that
without an hyperbole,
“_An undevout Astronomer is mad_[1].”
2. From this branch of knowledge we also learn by what means or laws the
Almighty carries on, and continues the admirable harmony, order, and
connexion observable throughout the planetary system; and are led by
very powerful arguments to form the pleasing deduction, that minds
capable of such deep researches not only derive their origin from that
adorable Being, but are also incited to aspire after a more perfect
knowledge of his nature, and a stricter conformity to his will.
[Sidenote: The Earth but a point as seen from the Sun.]
3. By Astronomy we discover that the Earth is at so great a distance
from the Sun, that if seen from thence it would appear no bigger than a
point; although it’s circumference is known to be 25,020 miles. Yet that
distance is so small, compared with the distance of the Fixed Stars,
that if the Orbit in which the Earth moves round the Sun were solid, and
seen from the nearest Star, it would likewise appear no bigger than a
point, although it is at least 162 millions of miles in diameter. For
the Earth in going round the Sun is 162 millions of miles nearer to some
of the Stars at one time of the year than at another; and yet their
apparent magnitudes, situations, and distances from one another still
remain the same; and a telescope which magnifies above 200 times does
not sensibly magnify them: which proves them to be at least 400 thousand
times farther from us than we are from the Sun.
[Sidenote: The Stars are Suns.]
4. It is not to be imagined that all the Stars are placed in one concave
surface, so as to be equally distant from us; but that they are
scattered at immense distances from one another through unlimited space.
So that there may be as great a distance between any two neighbouring
Stars, as between our Sun and those which are nearest to him. Therefore
an Observer, who is nearest any fixed Star, will look upon it alone as a
real Sun; and consider the rest as so many shining points, placed at
equal distances from him in the Firmament.
[Sidenote: And innumerable.]
5. By the help of telescopes we discover thousands of Stars which are
invisible to the naked eye; and the better our glasses are, still the
more become visible: so that we can set no limits either to their number
or their distances. The celebrated HUYGENS carries his thoughts so far,
as to believe it not impossible that there may be Stars at such
inconceivable distances, that their light has not yet reached the Earth
since it’s creation; although the velocity of light be a million of
times greater than the velocity of a cannon bullet, as shall be
demonstrated afterwards § 197, 216: and, as Mr. ADDISON very justly
observes, this thought is far from being extravagant, when we consider
that the Universe is the work of infinite power, prompted by infinite
goodness; having an infinite space to exert itself in; so that our
imaginations can set no bounds to it.
[Sidenote: Why the Sun appears bigger than the Stars.]
6. The Sun appears very bright and large in comparison of the Fixed
Stars, because we keep constantly near the Sun, in comparison of our
immense distance from the Stars. For, a spectator, placed as near to any
Star as we are to the Sun, would see that Star a body as large and
bright as the Sun appears to us: and a spectator, as far distant from
the Sun as we are from the Stars, would see the Sun as small as we see a
Star, divested of all its circumvolving Planets; and would reckon it one
of the Stars in numbering them.
[Sidenote: The Stars are not enlightened by the Sun.]
7. The Stars, being at such immense distances from the Sun, cannot
possibly receive from him so strong a light as they seem to have; nor
any brightness sufficient to make them visible to us. For the Sun’s rays
must be so scattered and dissipated before they reach such remote
objects, that they can never be transmitted back to our eyes, so as to
render these objects visible by reflection. The Stars therefore shine
with their own native and unborrowed lustre, as the Sun does; and since
each particular Star, as well as the Sun, is confined to a particular
portion of space, ’tis plain that the Stars are of the same nature with
the Sun.
[Sidenote: They are probably surrounded by Planets.]
8. It is no ways probable that the Almighty, who always acts with
infinite wisdom and does nothing in vain, should create so many glorious
Suns, fit for so many important purposes, and place them at such
distances from one another, without proper objects near enough to be
benefited by their influences. Whoever imagines they were created only
to give a faint glimmering light to the inhabitants of this Globe, must
have a very superficial knowledge of Astronomy, and a mean opinion of
the Divine Wisdom: since, by an infinitely less exertion of creating
power, the Deity could have given our Earth much more light by one
single additional Moon.
9. Instead then of one Sun and one World only in the Universe, as the
unskilful in Astronomy imagine, _that_ Science discovers to us such an
inconceivable number of Suns, Systems, and Worlds, dispersed through
boundless Space, that if our Sun, with all the Planets, Moons, and
Comets belonging to it were annihilated, they would be no more missed
out of the Creation than a grain of sand from the sea-shore. The space
they possess being comparatively so small, that it would scarce be a
sensible blank in the Universe; although Saturn, the outermost of our
planets, revolves about the Sun in an Orbit of 4884 millions of miles in
circumference, and some of our Comets make excursions upwards of ten
thousand millions of miles beyond Saturn’s Orbit; and yet, at that
amazing distance, they are incomparably nearer to the Sun than to any of
the Stars; as is evident from their keeping clear of the attractive
Power of all the Stars, and returning periodically by virtue of the
Sun’s attraction.
[Sidenote: The stellar Planets may be habitable.]
10. From what we know of our own System it may be reasonably concluded
that all the rest are with equal wisdom contrived, situated, and
provided with accommodations for rational inhabitants. Let us therefore
take a survey of the System to which we belong; the only one accessible
to us; and from thence we shall be the better enabled to judge of the
nature and end of the other Systems of the Universe. For although there
is almost an infinite variety in all the parts of the Creation which we
have opportunities of examining; yet there is a general analogy running
through and connecting all the parts into one scheme, one design, one
whole!
[Sidenote: As our Solar Planets are.]
11. And then, to an attentive considerer, it will appear highly
probable, that the Planets of our System, together with their attendants
called Satellites or Moons, are much of the same nature with our Earth,
and destined for the like purposes. For, they are solid opaque Globes,
capable of supporting animals and vegetables. Some of them are bigger,
some less, and some much about the size of our Earth. They all circulate
round the Sun, as the Earth does, in a shorter or longer time according
to their respective distances from him: and have, where it would not be
inconvenient, regular returns of summer and winter, spring and autumn.
They have warmer and colder climates, as the various productions of our
Earth require: and, in such as afford a possibility of discovering it,
we observe a regular motion round their Axes like that of our Earth,
causing an alternate return of day and night; which is necessary for
labour, rest, and vegetation, and that all parts of their surfaces may
be exposed to the rays of the Sun.
[Sidenote: The farthest from the Sun have most Moons to enlighten their
nights.]
12. Such of the Planets as are farthest from the Sun, and therefore
enjoy least of his light, have that deficiency made up by several Moons,
which constantly accompany, and revolve about them, as our Moon revolves
about the Earth. The remotest Planet has, over and above, a broad Ring
encompassing it; which like a lucid Zone in the Heavens reflects the
Sun’s light very copiously on that Planet: so that if the remoter
Planets have the Sun’s light fainter by day than we, they have an
addition made to it morning and evening by one or more of their Moons,
and a greater quantity of light in the night-time.
[Sidenote: Our Moon mountainous like the Earth.]
13. On the surface of the Moon, because it is nearer us than any other
of the celestial Bodies are, we discover a nearer resemblance of our
Earth. For, by the assistance of telescopes we observe the Moon to be
full of high mountains, large valleys, and deep cavities. These
similarities leave us no room to doubt but that all the Planets and
Moons in the System are designed as commodious habitations for creatures
endowed with capacities of knowing and adoring their beneficent Creator.
[Illustration: Plate I.