To know about the planets is to know about ourselves. The earth is one
of them. Whatever their origin, the earth’s is the same. It and they
are formed from the same nebula, controlled by the same central body,
subject to the same laws, and destined for the same fate in the end. In
this, the stars and the planets are not alike. They all shine upon us
with the same sweet friendliness, and commonly we make no difference
between them in our feeling for them. But the stars are bright and
beautiful acquaintances living far away in their own domain. The
planets are members of our own family, bone of our bone and flesh of
our flesh, living comparatively near to us, within the domain of our
common source of life, the sun.
One evening last autumn I was coming up Broadway, New York, with a
friend, when we encountered at Union Square a man with a six-inch
telescope directed toward the eastern sky. He was soliciting those
who passed to stop and look at Mars and Saturn. Both of these planets
were then very bright. They were also fairly near together, and so low
in the east that one could scarcely help seeing them. But the people
passed back and forth with hardly so much as a glance at the man and
his telescope, and for the most part never even raised their eyes to
the sky with a passing curiosity to see what it might be that he wanted
to show them. My friend and I stopped and took each a view first of
Mars and then of Saturn. While we were looking at the planets, a few
of the passers-by began to loiter about, half smiling at us for so
playing in public, slightly curious to see how we were faring at it,
but for the most part apparently indifferent to what we were seeing. We
had a fine view of Saturn lightly resting in his nest of rings, and an
equally good view of the comical “eye” of Mars.
After we had finished, one or two others, evidently prompted by our
example, followed us at the telescope. One or two inquired of us what
the stars were that had so interested us, and one, pointing to Mars,
wanted to know if it was Venus. As the crowd grew larger a few more
ventured to take a look, much as they might venture to take their
chance at hitting the bull’s-eye in some shooting-gallery. With the
telescope pointed at Saturn, the man droningly chanted: “This planet
is 887,000,000 miles from the sun. The ring you see is 170,000 miles
in diameter,” and so on. These, to be sure, were the facts--and most
marvelous facts, too--but without much meaning to one who knows nothing
much about the planets; and the manner of their recital certainly did
not make them alluring. I could not myself help feeling that the people
there were missing a valuable opportunity, and that it would be only
fair to them for some one fairly to cry out: “Come here and look at
this planet. It is different from anything else you have ever seen or
ever will see. It was at one time a part of the same nebulous mass
that we were a part of. It is in the same system of worlds with us. It
was formed in the same way that this world was formed. It is in itself
the most wonderful thing you ever saw, and it is bound, as we are, to
the sun by the ever-drawing tie of gravitation. The very position of
our own world in space is more or less influenced by it. If anything
should happen to it, it might be a serious matter to us.”
For it is true that we are thus closely bound to the planets. The
family tie among us is of far more force and significance than in any
ordinary case of common origin. Human family ties wear, as we know,
often into the merest threads, or even become no ties at all. But that
between the earth and the planets remains apparently as close and
strong as ever it was. The law of gravity, under which the earth draws
toward its center every atom of matter surrounding it, and thus holds
together all the atoms composing it, is not solely terrestrial in its
application. It is probably universal. It certainly applies to every
part of our little family of worlds. Every particle in the solar system
attracts toward it every other particle in that system with a force
determined by its mass and its distance. The sun, by reason of its
immense size, compels the earth and all the other planets forever to
circle around it. But the planets themselves have just as much power of
attraction as the sun, atom for atom.
Thus, while the sun controls the motions of all of them, each pulls at
the other, and, according to its power, determines how much the path
of each shall vary from the course around the sun it otherwise would
make. In the case of the smaller planets, this gravitational influence
is, of course, very slight, and so subtle that we here on earth are not
even conscious of it. But it is, nevertheless, real and continuous. It
is greatest between the two largest planets, Jupiter and Saturn; but
it was enough in the case of Uranus and Neptune to lead, by its mere
manifestation on the earth, to the discovery of Neptune, the farthest
planet.
Being thus of the same origin with the planets, having the same life
history, being bound to them in space by a tie that is perhaps eternal,
how can we fail to have the most intimate interest in their nature and
all that concerns them?
But in addition to their close relationship to us there is, to make
them of peculiar interest, the fact that, after the sun and the moon,
they are for our eyes the most splendid objects in all the brilliant
panorama of the sky. Such of them as we can see at all with the naked
eye are most of the time much brighter than any first-magnitude star.
As they wander from constellation to constellation the soft light of
their placid faces gives a beauty and variety to the spectacle that
endears them to us, and at the same time enhances by contrast their own
charm and that of the glittering, unchanging stars.
There is nothing that gives one such a sense of sweet familiarity with
the heavens as a really recognizing acquaintance with the planets. They
are not, like the stars, associated with particular seasons. They come
sometimes with the gay company of stars that dance their way across the
cold winter skies, and sometimes with those that shine during the soft
summer nights. Often in the spring and autumn we see some one of them
before the sun is fairly down, and, before the light of an ordinary
star can yet be seen, hanging in lone brilliancy as the evening star;
and often an early riser has the reward of seeing one as a morning star
glowing almost in the rays of the rising sun. Thus they are, one and
another, with us at all times and seasons, and it accords with the fact
of the relation being a family one that we have in their coming and
going a sense of frequency and informality which we cannot have in the
more regular and seasonal coming and going of the stars.