The Vermont watchman. [volume] (Montpelier, Vt.) 1883-1911, 1894-05-23
How Far Is the Sun.

the distance as 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
1863 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 ., 1000, 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 90, 500, 900 miles. But al
most century ago Laplace assumed
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 1000, 600 to 80, $50, 600 miles,
the difference between these extreme es-
Inmates being nearly as great as the 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
lance 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 i'll the future we shall not
see estimates of the suns distance vary
ing by millions of miles If q 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 at them from globe which is not
standing still, but is moving in an orbit
around the sun at the rate Of about ISL
miles in a second. Light travels 1856,
$50 miles in a second The ratio of the
velocity of the flying earth to that of
light measures the displacement i'll the
position of the stars that is called their
alteration. But, manifestly, if we can
learn precisely how far the earth travels
in second, we shall know just how
long its orbit is. We know that the earth
takes one year, or, more exactly, 81 Dos,
| $50 seconds, to go once around that or
bit. IT, 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 a circle, is an
ellipse, and that consequently the earth 5
rate of travelling varies 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 III its orbit to the
known velocity of light. If that aberra-
ton 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. 1873 seconds of arc.
This gives for the average velocity of
the earth in its orbit IS. 1859 miles in a
second, and for the distance of the sun
90, 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
1899, gives distance differing by only
so, 900 or 90, 600 miles from that shown
by the calculation based on the new
constant of alteration. So Laplace was
probably nearer to the truth than many
1t is evident that the final solution of
the great problem has not even yet been
obtained. There is an uncertainty of
perhaps as much as 100, 900 miles still
remaining. Since the distance of the
sun forms base line for calculating the
distance of the stars, an error Of 100, 900
miles in that base line would make a
difference of nearly 30, 900, 900, 900 miles
in the calculated distance of the nearest
fixed star in the sky. 1t is for the as
tronomers Of the future then, to deter
mine the real dimensions of the uni
verse, if they can. For our part, we
must be content to know that they are
great almost beyond the power of math-
ematics to express and certainly be-
yond the power of imagination to con-
ceive -Ne,o York Sun.