The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1894-05-16
How Far of Is the Sun.

A little new light has recently been
thrown on the problem Of the distance
of the sun. Thi, is the great yard
stick of astronomy. For more than a
century every effort has been made to
ascertain the distance as accurately as
possible. Methods direct and indi-
rect have been employed. Consider
ing the fact that the knowledge sedu-
ously pursued can serve no utilitarian
purpose, the generous expenditure in
the pursuit does credit to the intel
lectual aspirations of the human race.
From the time of Capt. Cooks expe-.
dition to the Society Islands to OBJ
serve the transit of Venus in 1869
until the present day, millions Of dol
lars have been spent in this effort to
drop sounding line to the sun.
Copernicus believed that the sun
was not more than 5,O0O,000 miles
away. There were philosophers be-
fore the Christian era who knew as
much as that. For several years past
we have been assured that the distance
could not be far from $780, 1000
miles. But almost a century ago,
Laplace assumed a parallax for he
sun which gave almost exactly tnat
distance. Since his time various
astronomers have attacked the prob
lem, and their results have varied
from 81, 100000 to 5000, 900 miles,
the difference between these extreme
estimates being nearly as great as the
entire distance was believed to be by
the founders of astronomy. Yet these
facts carry mo- challenge to the sound
ness of modern astronomical methods,
or the substantial correctness OF the
results attained by them. The dis
tance of the sun is not yet known
with absolute accuracy, for the same
reason that the height of Mount st.
Elias or of Mount Everest has not yet
been exactly ascertained. But the
limits of error are known, and in the
fnture we shall not see estimates OF
the suns distance varying by millions
of miles. If series Of wires should
be cut, each agreeing in length with
one of the recent measures OF the So
lar parallax, and all should then be
stretched from the earth toward the
sun, every one Of them would end in
the sun, though none might stop pre-
cisely at its centre.
AS to the recent light upon this
problem it is furnished by the results
Of observations by officials of the
United States Coast Survey at the
Sandwich Islands, to determine the
constant of alteration Of the stars.
By this is meant the amount of dis
| placement that the stars undergo in
consequence Of the fact that we are
| looking at them from globe which is
not standing still, but is moving in an
orbit around the sun at the rate OF
| about 184 miles in second. Light
travels 1856, $50 miles in second.
The ratio Of the velocity Of the flying
earth to that Of light measures the
displacement in the position Of the
stars that is called their alteration.
But, manifestly, if we can learn pre-
| cisely how far the earth travels in a
| second, we shall know just how long
| it's orbit is. We know that the earth
| takes one year, or, more exactly, 81,
SIS, ,15O seconds, to go once around
that orbit. If, then, we can lind out
with rigorous accuracy how far it goes
| in a second, we can at once calculate
not only the length of the orbit, but
the distance of the sun, which de-
pends directly upon the size OF the or
bit. Of course, allowance must be
made for the fact that the orbit, in
stead of being a circle, is an ellipse,
and that consequently the earth s rate
of travelling varies little. But
mathematics takes care of that.
Now, we have seen that the dis
placement, or alteration, Of the stars
| furnishes means of determining the
ratio of the earth's velocity in it's or
bit to the known velocity Of light.
If that alteration is accurately meas
ured, it must give, by simple calcu,
lation, the velocity Of the earth and
the distance of the sun. The aberra-
tion as ascertained at the Sandwich
Islands is slightly smaller than preyl-
Gus measurements had made it. 1t
amounts to 20,433 second OF arc:
This gives for the average velocity OF
the earth in it's orbit 1874 ,582 miles in
a second and for the distance OF the
sun, 92, zoe, 900 miles. The distance
derived from the observation Of the
transit of Venus in 1874 was about
$40, 900 miles less than this, while
that calculated from the transit OF 1857
was about 1870, 900 miles greater. But
Laplace's value of the solar parallax,
adopted by him in 1899, gives dis
tance differing by only $4,000 or 9O,-
| 600 miles shown by the calculation
based on the new constant OF abberra-
9ion so Laplace was probably nearer
to the truth than many OF the later
astronomers have been.
1t is evident that the final solution
of the great problem has not, even yet,
been obtained. There is an uncertain
ty of perhaps as much as 100, O,0oO
miles still remaining. Since the dis
tance of the sun forms a base line for
calculating the distances Of the stars,
an error of 1000 miles in that base
line would make difference of nearly
thirty thousand million miles in the
calculated distance of the nearest
fixed star in the sky. 1t is for the
astronomers of the future, then, to
determine the real dimensions Of the
universe, if they can. For our part,
we must be content to know they are
great almost beyond the power OF
mathematics to express, and certainly
beyond the power of imagination to
nceiye.-New York Sun.
| yfo,1 lo,,o ~,