The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1900-05-26
PHYSICAL CONSTITUTION OF THE
SUN.


SUN.
The question of the chemical con-
stitution Of the sun, and it's physical
| state, whether solid, liquid or gaseous
seemed but few years since to be be-
yond the reach of science. But in the
| hands of skilled astronomers the spec
| troscope has answered these and many
other interesting questions. A brief
| description of the principle OF this
! instrument will help in a measure to
understand how these results are OBJ
| tanned.
If sunlight coming through a small
| hole in a dark room passes through a
glass prism and the light then falls on
| sheet of white paper, it will be
be found to be drawn out into a rain
bow -coored band OF light, red at one
end. violet at the other, with the rest
| of the colors between. This is the
spectrum Of sunlight. Examined, how
| ever, merely as above described, the
| spectrum Is impure, adjacent colors
| overlap. BY means OF the spectro-
scope this overlapping Of colors is pre-
| vented. This instrument consists es-
sentially OF a narrow slit about one
one thousandth of an inch wide, on
! which the light to be examined falls,
a prism, usually of glass, which di-
| vides the light coming from the slit
into it's constituent colors, and teles-
cope for examining the light after
passing through the prism. BY means
| of such an instrument ii is found
| that the light from a white-hot solid,
| liquid. OF gaseous body, under great
| pressure, always gives a continuous
| spectrum, that is, an unbroken band
| OF colOrs, spectrum from which no
! color is missing. When, however, the
! light of an inCandesccnt gas, such as
| apodium, or magnesium flame, an
| electric spark or an electric arc is eX-
amined, there is no cohtiuous spectrum
but instead a series of bright lines.
| Every element gives its characteris-
| tic bright line spectrum.
If now this incandescent gas be eX-
amined against the brighter back
/ ground of a whte-hot solid or IL
quid substance, hotter than the gas
| there is seen a continuous spectrum
| interrupted by dark lines which coin
| eide exactly with the bright lines Of
| the gas. Now on examining sunlight
| with the spectrosCOpe, We find 1t has a
| continuous spectrum, broken by many
| fine, dark lines, which coincide with
the lines of the spectra of a number
| OF known terrestrial elements. We
may, therefore, confidently say that
! that these elements are present in the
| solar atmosphere as incandescent
gases.
How accurate this method is will in
| part appear from the fact that the ele-
ment helium was first found on the
sun and only later traced to earth.
Among the clements discovered on the
sun are potassium, sodium, magnesium,
nickel, cobalt calcium, silicon, titanum
carbon, oxygen, copper platinum and
| iron, Professor Rowland, who has
made an extensive study of the solar
| spectrum, says that If the earth were
| heated as highly as the sun it would
give precisely the same spectrum.
TO THE EYE AND CAMERA.
Visual Photographic observations of
| the sun show that its brightness de-
| creases from the center toward the
| limb, owing to the greater depth Of
solar atmosphere through which the
latter is seen. 1t is found that less than
one-half as much light and heat as is
radiated at the center is given off at
the limb of the sun. The action OF
| the solar atmosphere is found to be
similar to our own. Less of the violet
| light penetrates it than of the red.
Under the influence OF the intense
| heat the suns atmosphere is kept in
a state of violent disturbance in COM
parison with which Western cyclones
and West Indian hurricanes are mere
zephyrs, Two photographs of the sun,
the one taken ten minutes after the
other, disclosed an evident change in
the solar surface. which, to be detected
at all, even under the most favorable
| conditions, implied a motion of at least
| AZ miles.
The visible surface of the sun is