The times. [volume] (Washington [D.C.]) 1897-1901, 1900-06-10
STARS and SATELLITES
Remarkable Work Achieved by
Students of the Skies.
Marvels in the Heavens Brought to
View by the Use of the SPectrO-
xcOpe-COnstructiOn of the Won
dcrful Astronomical Instruments
Chemical Analysis of Light Rnys.

What will not the intellect of man
attain What will we get at next?" are
questions constantly being asked, and con-
stantly receiving more wonderful replies
That the light OF reason. that same mental
quality which demonstrates a proposition
of Euclid. can mount through the infinite
void of space. can seize upon a body NOV
ing far above the reach of mere physical
sight. and weigh that body. determine It's
orbit of motion to hairbreadth nicely
and establish forever its position in the
universe, seems certainly to transcend the
most marvellous feats Of genii or sprite
recorded in the Arabian Nights tales. Yet
such feats are now included In the crdi-
nary routine of astronomical science. and
their accomplishment. depending upon
mathematical calculation, is a beautifully
simple process when understood. 1t has
long been known that there are in the
heavens what are called variable stars.
obscured for certain periods, becoming Wis
ible again after a short Interim of dark
ness.
Astronomers reached the conclusion that
this appearance, or disappearance. in the
case of these stars was due to the inter-
position Of q dark body between the star
and the eye Of the spectator. When it was
noted. in connection with this suppOsition.
that certain perturbations were visible in
The bright star which showed that its mo-
ton must be relative to some adjacent
body, it became a reasonable certainty that
.-t.. ~ \ 4
was dark body, which rendered it in
capable of detection by means of the tele-
scope, camera, or spectroscope
So much known, the next thing was to
determine the size and orbit of the invisI-
BILE satellite. This with the aid of the
higher mathematics was not difficult. The
variations in the light and motion Of the
visible star were the known factors en-
ployed in the calculation, and, these being
in direct reference and proportion to the
unknown, soon, by comparison, established
the latter with the minutest accuracy.
Another most remarkable and recent
achievement is astronomy, and one which,
among many others, have been rendered
possible by the speetroscope, is the deter
mination of double stars when one is COM
pletely hid behind the other or when the
distance separating them is so, small III
comparison with their immense altitude
above the earth as to be indistinguishable
even with the aid of the most powerful
telescope or camera. In order that the
method employed for the determination OF
these double stars may be completely I'M
derstood by those not yersed in the tech
nicalities of astronomical science it may be
well to describe the nature of the spec
troscope.-
1t is only very recently that astronomers
have come to recognize the real value OF
this marvellous instrument, and it is now
used in almost all fields of astronomical re-
search. Without entering into detail it
may be explained that the spectrum OF
heavenly bodies records the chemical COM
ponents which constitute their light The
instrument itself. the speotroscope. con-
sists of three telescopes cnnverging to-
ward prism, and upon looking through
the eye piece of one Of these the prismatic
colors produced by the light under observa-
ton are seen upon screen, In parallel
bands. This prismatic effect or spectrum,
as it is called, is really a chemical analysis
Of light, and may be produced by ignited
solids or liquids, called a continuous spec
trum ignited gases or vapors, and known
as the band or line spectrum. or the light
of the sun and fixed stars, which is called
an absorption spectrum.
These spectra differ in color and regulari-
it was found, therefore. in the spectra OF
certain stars, that these lines showed
marked variations horizontally and that
the colors blended irregularly 1t became
apparent. upon investigation. that not one
but two spectra were obtained emonstrat-
ing the existence Of double star. BY con-
slant experimentation the respective po-
sitions of each of these stars Can now be
determined. and in some cases two. and
even more have been found. thus closely
related in space.
The remarkable achievements of the
spectroscope in past solar eclipses led to
its wider employment in the great eclipse
of May % than ever before. One OF the
most notable Of its triumphs was the dis
covery, by its means. of the true nature Of
the protuberances or solar prOminences
which appear during an eclipse OF the sun
as mountains or cloud-shaped luminous
objects. varying in size. and surrounding
the moons disc.
During the eclipse Of 1868 it had been
by Jannsen that protuberances
emitted certain bright lines coinciding with
those of hydrogen. They have. however,
been fully understood only since Sir Nor
man Lockyer and Thomas Jannsen discov-
cred q method OF investigating them at any
time by the aid of the spectroscope more
than could be done with the
telescope aided by an eclipse.
The principle Of this method Is as fol-
lows: When line Of light admitted
through a slit is decomposed by a prism.
the length Of the spectrum may be in
by passing it through two or more
prisms. As the quantity of light is neces-
sarily the same. it Is clear that the in
tensity of the spectrum will be diminished
This is the case with the ordinary sources
ha iub,
homogeneous 1t will be merely deviated,
and not reduced in intensity by dispersion;
and ii the source of light amt lights of
both kinds. the image Of the slit of light
Of definite refrangibility, which the mix
ture will contain, will stand out by its
superior intensity on the weaker ground
of the continuous spectrum. This is the
Ease with the spectrum of the pro-
tuberances. Viewed through an ordinary
picturesque, the light they emit is over
;hadowed by that of the sun; but by using
)risms Of great dispersive power the suns |
light becomes weakened, and the spectrum
Of the protuberances may be observed. |
Lockyers researches leave no doubt that |
-hey are ignited gas masses, composed |
principally of hydrogen. BY altering the |
position of the light slit in the spectro- |
scope series OF sections of the promi- |
1ences are obtained, by collating which |
he entire form of each prominence may be
Inferred. They are thus found to enclose
he sun usually. to depth of about 1000
niles. but sometimes in enormous local ac-
which reach the height of
$1,000 miles. These phenomena have not
merely been examined on the edge of the
Jun. where they are alone visible during
IN eclipse. but upon the face of the disc
tself. They have been shown to be the
'esults of certain outbursts OF storms.
which move with the enormous velocity of
20 miles in second
Just what the spectroscope may have
disclosed during the recent eclipse. es-
,eciallY in regard to the corona 81 ~. |