The Ohio Democrat. (Logan, O. [Ohio]) 1886-1906, 1890-03-15

distance OF star; the earth in her wide
circuit round the sun is in winter or
the opposite side of the sun to what she
was in summer, and consequently the
earth's distance from the sun being
about ninety-one million miles, we see
the stars from two different points oi
view, one hundred and eighty millions
of miles apart. But vast as is this base.
line, any change in the position of a
star is, with one or two exceptions, al
together inappreciable, and Sirius
stands barely within the limits of any
approximate estimation In fact, this
star, viewed from the two extromes of
the earth's orbit, shows a displacement
of position equal to about the five
thousandth part of the moons diameter,
so that it is almost impossible for as
tronomers to determine the distance OF
dimensions of Sirius by this means.
| Bright as the Dog-star appears to the
naked eye, in the telescope 1t appears as
a mere point of light; and even in the
largest telescopes constructed, though
its light is greatly increased, definite
disc or outline, as is seen in the planets,
is quite undiscernible; for If the power
of telescope was sufficient to ''raiso n
disc on the star, it would be almost an
impossibility to distinguish it, owing to
| its great brilliancy; for as Sir William
| Herschel tells us, when Sirius was about
| to enter the field of view of his forty
| feet reflector, "the light resembled that
which announces the approach of sun
| rise;" and when the star was in the field
of view sit appeared in all the splendor
@ ,,,s,
sible to behold it without pain to the
eys."
Now, If astronomers could measure
the disc Of Sirius, they could from that
determine its distance and measure its
dimensions; but as no outline is appreci-
able, they resort to comparing the light
received from this star with that which
we receive from the sun, and by this
means they are able to form some con-
clusion as to it's probable size. After
the most careful comparison of the
light of Sirius, the sun and other stars,
astronomers agree in fixing the volume
of Sirius as exceeding our sun nearly
FIVE thousand times, and his diameter
as exceeding our suns seventeen times,
so that the diameter of this giant orb is
lO lcSo ONtE uEISeh H11R-
lions of miles!"
To the philosophers and scientists of
the last century, it must have appeared
incredible that at any future time scien-
tific discoveries would have enabled us
to tell with certainly the composition of
the stars. Yet during the last fifty
years the science of spectrum analysis
has so far advanced as to give us unde-
niable proof of the existence of certain
elements in the sun and also in the
stars, similar to those with which we are
acquainted on earth. AS DIR. Higgins
says: "We now need not teach our chill
dren that little couplet Twinkle,
twinkle, little star, how wonder what
you are' because we really know; we
have in the place of wonder, knowl-
edge" OF this method of ascertaining
the composition of distant body by it's
light, it is sufficient here to remark that
it is due to the fact that, when ray of
light has by means of the spectroscope
passed through glass prism, 1T is
spread out into broad band comprising
all the colors of the rainbow. This
band or spectrum is in the case of the
sun and other similar bodies crossed by
number of fine dark linesswhich cor
respond to the various elements present
in their constitution. Now, if certain
gases, such as hydrogen or sodium, be
burnt and their spectra examined, lines
similar to those in the SUMS spectrum
will be found; and If the two are COM
pared, the presence or absence of such
elements in the sun may be inferred.
By this means of spectrum analysis 1t
has been found that the sun contains q
large number of terrestrial elements, in
Guiding hydrogen, iron, sodium, magne"
sium, zinc, lithium, copper, oxygen and
many others; of these, the first four
mentioned have been discovered in
Sirius; and doubtless most of the others
exist also, as the spectrum of this star
resembles that of our sun in all essen
tai respects, though it can not be OBJ
served under the same favorable con-
ditions.
BY means of the spectroscope very
wonderful discovery had been made re-
specting Sirius. Astronomers has no
ticed that this star was in rapid motion
through space, as it was found that year
ty year it was changing its position in
the he. s. traversing in about fifteen
hundred years a space equal to the ap-
parent diameter of the moon, at veloci-
ty of no less than twenty miles per |
second. OF course, by actual observa-
tion the only motion capable of being |
detected would be that which was square
to the line of sight, so that although |
Sirius appears to us to move across the
heavens, he may really be travelling in
a slanting direction, either towards or
from us. No one would ever have ex-
pected to be able to tell whether a star
was approaching to or receding from us,
yet even this seemingly ipsolvable prob
lem has of late years been accomplished
by the spectroscope. DR.. Higgins, our
greatest authority on this subject, hav-
ing identified certain lines in the spec
trum Of Sirius as those of hydrogen,
found on comparison that these were
displaced in such manner as to indi-
cate that the star was receding from u.s.
1t has been estimated that this recess
sion combined with the thwart motion
of twenty miles per second, gives as the
actual movement of Sirius in space
speed OF about thirty-three miles per
second.
These, then, constitute some of the
chief items of information about Sirius
at present within our knowledge.