The star. (Reynoldsville, Pa.) 1892-1946, 1894-04-25
HOW FAR is THE SUN
NeWLlGHTWHlcH n HAS BEEN THROWN
ON THE PROBLEM.

Results of Observations Made by the Coast
Survey nt tho Sandwich rslnnds-The Dis
tance TO the SUP Is Something Like Nine
ty-fve Million Miles, More or Less.
A little new light has recently been
thrown on the problem Of the distance
Of the sun. This is the great yardstick
Of astronomy. For moro than u century
every effort has been made TO ascertain
the distance rs accurately as possible.
Methods direct and indirect have been
employed. Considering the fact that the
knowledge thus sedulously pursued can
serve no utilitarian purpose, the gener-
Gus expenditure in the pursuit does
credit to the intellectual aspirations of
the human race From the time of Cap
tain Cooks expedition to the Society is.
lands to observe the transit of Venus in
1869 until the present day millions Of
dollars have been spent in this effort to
drop sounding line TO the sun.
Copernicus believed that the sun was
not more than 3, 900, 900 miles away.
There were philosophers before 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 %, 500, 900 miles. But al
most a century ago Laplace assumed a
parallax for the sun which gave almost
exactly that distance. Since his time
various astronomers have attacked the
problem, and their results have varied
from 0l,000, 900 TO 05, ESQ, 900 miles,
the difference between these extreme es-
Inmates being nearly as great as tho en-.
tire distance was believed to be by the
founders of astronomy
Yet these facts carry no challenge TO
the soundness 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 tho limits of error are
known, and in the future we shall not
see estimates of the suns distance vary
ing by millions of miles. If a series Of
wires should be cut, each agreeing in
length with one of the recent measures
of the solar 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 precisely
at its center.
As to the recent light upon this prob
lem, it is furnished by the results of OBJ
servations by the United States coast sur
vey at the Sandwich Islands to deter
mine the constant of alteration of the
stars. By this is meant the amount of
displacement that the stars undergo in
consequence of the fact that we are look
ing ut them from globe which is not
standing still, but is moving in an orbit
around the sun at the rate of about 1SL
miles in second. Light travels 1856, =
$50 miles in n 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 precisely how far the earth travels
in a second, we shall know just how
longits orbit is. We know that the earth
takes one year, or, more exactly, 81, 558, =
100 seconds, to go once around that or
bit. If, then, we can find out with rig
orous accuracy how far it goes in a Sec
ond, we can at once calculate not only
the length of the orbit, but the distance
of the sun, which depends directly upon
the size of the orbit OF course allow
ance must be made for the fact that the
orbit, instead of being circle, is an
ellipse, and that consequently the earth s
rate of travelling varies a little But
mathematics take care of that
Now, we have seen that the displace-
ment, or alteration, Of the stars fur
nishes means Of determining the ratio
of the earth's velocity in its orbit to the
known velocity Of light. If that aberra-
tiOn is accurately measured, it must
give, by simple calculation, the veloc-
ity of the earth and the distance of the
sun The alteration as ascertained at
the Sandwich Islands is slightly smaller
than previous measurements had made
it, 1t amounts to 20. 433 seconds of arc.
This gives for the average velocity of
the earth in its orbit lS. 4582 miles in a
second, and for the distance of the sun
92, 700, 900 miles. The distance derived
from the observation of the transit of
Venus in 1874 was about 620, 900 miles
less than this, while that calculated
from the transit of 1882 was about 100, :
900 miles greater. But Laplace's value
of the solar parallax, adopted by him in
1893, gives distance differing by only
80, 600 on 90, 600 miles from that shown