Morning journal and courier. [volume] (New Haven [Conn.]) 1848-1894, 1882-08-05
The Boundaries of Astronomy

Professor Ball in the Contemporary Review.l
The star sweeps along through our system
with stupendous velocity Now there can be
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 leaving our system, would retreat into
the depths of infinite space. Is there any
power adequate to recall this star from the
voyage to infnity? We know of none, I'M
less it be the attraction of the stars or other
bodies of our sidereal system. 1t therefore
becomes a matter of calculation to determine
whether the attraction of all the material
bodies of sidereal system could be ade-
quate, even with universal gravitation, to re-
call body which seems bent on leaving that
system with velocity of two hundred miles
per second. This interesting problem has
been discussed by Professor Newcomb,
whose calculations we shall here follow. In
the first place, we require to make some esti-
mate of the dimensions of the sidereal sys-
TEN, in order to whether it seems likely
that this star can ever be recalled. The
number of stars may be taken at 100, O0O 900,
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 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 pre-
sumed to be disposed in fat circular layer
of such dimensions that ray of light would
require 3d. 900 years to traverse one diameter.
Assuming the ordinary law of gravitation, it
is now easy to compute the efficiency of such
| an arrangement in attempting to recall
moving star. The whole question turns on
certain critical velocity of twenty five miles
second. If star darted through the system
we have just been considering with velocity
| less than twenty five miles second, then,
after that star had moved for certain dis
lance, the attractive 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 velocities of the
stars were under circumstances more than
twenty-five miles second, then, supposing
| the system to have the character we have de
| scribed, that system might be always the
same. The stars might be in incessant mo.
ton, but they must always remain in the vi
cinity of our present system, and our whole
sidereal 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 mics second If this star dash
| through the system, then the attractions of
| all the bodies in the system will unite in one
traction must, to extent, be acknowl-
| edged the speed of the wanderer must grad
ually diminish as he recedes into Space but
| that speed will never be lessened sufficiently
| to bring the star back again. AS the star
treats further and further the potency of the
| attraction will decrease, but, owing to the
velocity of the star being over twenty-five
miles second, the attraction can never OYER
come 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 bodies
| which form our sidereal system. That esti-
! mate was founded on a liberal, 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 a hundred million stars in our
system; their average weight may be more
| than five times the weight of our sun. But
unless the assumption we have made is enor-
| mously short of the truth, our infer encs can
not be CHALLENGED.