DENSITY AND GRAVITATION.
1st. _Density._ The sun’s density is one-fourth that of earth, while
Mercury’s is one-fifth greater than earth’s, showing that Mercury’s
substance must be more than five times denser than the sun’s, whereas
it is not 36,000,000 miles distant from it; so near, in fact, and so
recently thrown off from the sun as to be thought that human beings
could not live upon it. Why is it that this dense substance did not,
while a portion of the sun, sink to its centre?
It might be said that on cooling, after being thrown from the sun, the
body became more and more dense, the same as is said of earth. But if
so why is it that Neptune, seventy-five times farther from the sun, has
a density only one-fifth that of earth, and Uranus but a little more;
while Jupiter’s density is less than the sun’s, and Saturn’s not even
one-seventh that of earth? All of these planets lie in an immensely
cold and far away region and were thrown off by the sun, if at all,
many years before Mercury, and, according to the supposed theory,
should be cold bodies.
Some think, with apparent show of reason, that before planet-making
began the heavier materials of the general mass had gravitated toward
the centre, while the lighter substances remained near the surface.
“If so,” to quote the words of Prof. Winchell, “the first planets
separated would contain more of the substances which, at temperatures
familiar to us, make gases and water. Similarly, the later planets
disengaged would acquire a large proportion of the substances which
form solid rocks. In the case of the earth we may suppose that the
greater part was rock-making material, since the earth’s specific
gravity is so high; but watery stuff in sufficient amount to provide
for oceans and rains, went off with the rock-material, and with these,
the lighter stuff for an atmosphere. But in the case of Venus, most
of the stuff was rock-material, if not the whole of it; while with
Mercury it seems probable that little water-stuff was included. In the
opposite direction, Saturn, Uranus, and Neptune must have received a
large excess of water and atmospheric stuff. It is rational to suppose
that their oceans have always covered the whole land, as ours does more
than half. In fact, these bodies must be composed chiefly of water and
atmosphere; as their specific gravities are low as water and cork.”[4]
Now if this is a good explanation what shall we say of the sun from
which these planets were separated? If it grew more and more solid as
it contracted until Mercury, nearly ten times denser than Saturn, was
thrown off, why is not the sun denser than Mercury? whereas we find it
with but one-fourth the density of earth.
When the sun reached out to earth it must have had a diameter of nearly
200 million miles, but having now contracted to a diameter of less than
one million of miles, should it not have a density ten times greater
than earth’s, instead of one so much less? For if the solid parts when
out at Neptune began to fall toward the sun’s centre, they should
have continued to fall until they reached it, or until they had met
a density greater than their own. We must remember even at the sun’s
present surface a body would fall with much greater velocity than on
earth’s surface because of its greater weight. With the density of our
earth more than five times that of water, and twice that of solid rock,
all heavy substances must gravitate toward its centre; whereas on the
surface of the sun the gravitation is more than 27 times stronger. If
then the sun were ever a fire-mist reaching out to earth, it would
seem that nothing should have prevented the earth from falling with
lightning-like speed to the sun’s centre, as its volume was 8,000,000
times larger than now, and even its present volume would hold 900
thousand worlds like ours before it would have a like density.
2d. _Gravitation._ We see the sun to-day as a perfect sphere, but does
a body that is a sphere ever throw off rings by rotary movement? When a
body in its revolutions throws off rings by rotating, instead of being
spherical it is of a flattened, or grind-stone shape, and the rings are
hurled from it by the centrifugal force overpowering the gravitation;
hence we cannot think that the sun’s rings,—being of enormous
circumference and necessarily of a light or fluid substance in order
to be thrown off,—could form into spheres unless the centrifugal force
was extremely great.
Let us suppose that Neptune was thrown off from the sun as a ring, like
those we see around Saturn; and, as it is now about 3,000 millions
of miles distant from the sun’s centre, before it was detached it
must have had a diameter of about 6,000 millions of miles, with a
circumference of over 18,000 million miles. Now, as Neptune has about
100 times the volume of earth,[5] its ring could have been no more than
40 miles square; for 1600 square miles multiplied by 18,000 million
miles, the distance around that ring, will give more than Neptune’s
volume. How then could any substance so exceedingly thin draw to itself
this enormous distance of 18,000 millions of miles, any more than a
thread a thousand miles in length could draw itself together into a
ball, without the thread’s breaking into a million pieces?
Or, take another theory, and instead of supposing that the sun threw
off rings, suppose that its surface cooled and formed into a hard
crust. Had the inner sun then shrunk away from the outer could that
crust have ever formed into a globe that would rotate around the inner
sphere, and if not how could Neptune have been formed? Should such
a crust have extended around the sun while spread out to Neptune it
must have had a circumference of over 18,000 million miles, as did the
ring, with a surface of 108 quintillions of square miles; so the crust
could not have exceeded one-sixtieth of an inch in thickness. If, then,
Neptune’s substance in any way resembles earth’s, with a crust of that
thickness upon the sun’s surface, it must have collapsed in millions of
places instead of having broken away from the sun and formed the globe
that we now behold. Chambers tells us: “At the surface of the earth a
body set free in space falls 16.1 ft. in the first second of time, with
a velocity increasing during each succeeding second. A body similarly
set free at the surface of the Sun would start with a velocity 27.4
times as great as that of a body falling at the surface of the Earth.
This is equivalent to saying that a pound’s weight of anything on
the Earth would, if removed to the Sun, weigh more than 27 lbs. The
centrifugal force, due to the rotation of any body diminishes gravity
at its surface. At the Earth’s equator the total diminution is 1/289
part; whilst at the Sun’s equator the centrifugal force is only about
1/18,000 part the force of gravity. It would be necessary that the Sun
should turn on its axis 133 times quicker than it does, for the force
of gravity to be neutralized. In the case of the Earth, however, a
speed of rotation 17 times as great as it is would suffice to produce
the same result.”[6]
By this it is seen the centrifugal force is comparatively insignificant
with the sun revolving faster than ever before; for, on the principle
that the more a body contracts, the swifter it revolves, it must
revolve several hundred times faster now than it did when its
circumference was at Neptune’s bounds. If this be the case it is
difficult to believe there was ever a time that the sun could have been
larger than at the present, and have had centrifugal force enough to
throw off rings from its surface.
[Illustration: Decoration]
FOOTNOTES:
[4] Winchell, “Walks and Talks in the Geological Field,” p. 217.
[5] Steele’s “New Descriptive Astronomy,” p. 174.
[6] Chambers’ “Hand Book of Astronomy,” p. 6.