Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1882-08-31
The Boundaries of Astronomy.

! oyotOn Will VctOClCy. NOW
| there can be no doubt that if the star
were permanently to retain this velocity
| it would in the course of time travel
right across our system and after leav-
| ing our system would retreat into the
depths of infinite space. Is there any
| power adequate to recall this star vow
age to infihity? We know of none, un-
| less it. be the attraction of the stars or
other bodies of our sidereal system. It,
therefore, becomes matter of calcula-
ton to determine whether the attraction
of all the material bodies of our sidereal
system could be adequate, even with
universal gravitation, to recall body
| which seems bent on leaving that sys-
tenn with velocity of 200 miles per
second. This interesting problem has
been discussed by Professor Newcomb,
whose calculations we shall here fol-
low. In the first place we require to
make some estimate of the dimensions
of the sidereal system, in order to see
whether it seems likely that this star can
ever be recalled. The number of stars
may be taken at 1OO,OOO,OOO, which is
probably double as many as the number
we can see with our best telescopes.
The masses of the stars may be taken as
on the average five times as great as the
mass of the sun. The distribution of the
stars is suggested by the constitution of
the milky way. One hundred million
stars are presumed to be disposed in a
fiat circular layer of such dimension
that ray of light would require 10000
years to traverse one diameter. AS
Stunning the ordinary law of gravitation,
it IS now easy to compute the efficiency
OF such an arrangement in attempting
to recall a moving star.
I The whole question turns on a certain
critical velocity of twenty-five miles
second. If a star darts through the
system we have just been considering
with velocity less than twenty-five
miles 8 second, then, after that star had
moved for a certain distance, the at
tractive power of the system would
gradually bend the path of the star
round, and force the star to return to
the system. If, therefore, the veloci-
ties OF the stars were under no circum-
stances more than twenty-five miles a
second, then, supposing the system to
have the character we have described,
that system might be always the same.
The stars might be in incessant mo-
ton, but they must always remain in
the vicinity of our present system, and
our whole sideral system might be an
isolated object in space, just as our solar
system is an isolated object in the
extent of the sidereal system. We have,
however, seen that for one star at all
events the velocity is no less than two
hundred miles a second. If this star
dash through the system, then the at
fractions of all the bodies in the system
will unite in one grand effort to recall
the wanderer. This attraction must to
some extent be acknowledged, the
speed of the wanderer must gradually |
diminish as he recedes into space; but |
that speed will never be lessened suffic- |
iently to bring the star back again. AS |
the star retreats further and further the |
potency of the attraction will decrease, |
but, owing to the velocity of the star
being over twenty-five miles a second,
the attraction can never overcome the |
velocity; so that the star seems |
destined to escape, This calculation is,
of course, founded on our assumption as
to the total mass of the stars and other i
bodies which form our sidereal system.
That estimate is founded on a liberal, I
indeed, a very liberal, Interpretation of |
the evidence which our telescopes have
afforded. But it may still fall short of |
the truth. There may be more than
hundred million stars in our system;
their average weight may be more
than our sun. But unless the assump-
ton is enormously short of the truth,
our inference can not be challenged.-l
Prof. Ball, IN the Contemporary Review.
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