Evening star. [volume] (Washington, D.C.) 1854-1972, 1900-11-03
in the accounts of the surface details of
Mars, Jupiter. ETC.
Study of the Comets.


Mars, Jupiter, etc.
Study of the Comets.
In the study of the physical character
istics OF comets also photography has
proved to be of the very first Importance.
Features quite impossible to see with the
eye are distinctly shown on the negative
plate, and in this field We are on the very
verge of great discoveries. The connection
of comets with meteor swarms IL a fact
of capital Importance.
The electric telegraph has revolutfoniZed
certain parts of astronomy and geodesy.
All longitudes are now fixed by the
American method" with unheard-of ac-
curacy and rapidity, and the figure of our
81 be will soon be well determined One
of the striking discoveries of the century
Is DR.. Chambers detection of a minute
regular change of the axis of rotation of
the earth whose effect Is shown in regu-
lar. though small, variation of the lau-
tudes of places. This discovery is an eX-
cellent example of the thoroughncss with
which all astronomical work, both obser-
walton and calculation, Is now performed.
Planets and Stars.
At the beginning of the century Sir
William Herschel was in midcareer. He
discovered the planet Uranus in 1871; its
two brighter satellites were discovered by
him in 1877; the two innermost satellites
of Saturn in 1889 The satellite of Nep-
two more satellites to Uranus, again by
Lassell, in 1851; satellite to Saturn by
Bond in 1S4S; two satellites to Mars by
Hall in 1877; satellite to Jupiter by Bar
nard in 1892; a ninth satellite to Saturn by
Pickering in 1899.
Newton's discovery Of universal gravita-
ton reached no further than the outer
most planet known to him, Saturn. The
discovery Of Uranus and Neptune extend
ed the scope, but Herscheps detection of
systems of binary stars revolving about
each other according to this law made
gravitation truly universal: the law was
effective to the boundaries of the universe.
Our knowledge of double stars has been
vastly extended by the discoveries of this
century. Thousands Of such systems have
been discovered and many orbital motions
are already calculated.
To Herschel a star was a shining body
like the sun. both being Of unknown con-
stitution. The spectroscope Invented by
Bunsen and Kirchhoff in 1859 brought a
new engine to bear on problems until then
utterly unsolvable. The spectrum of the
sun. or of star. compared with the spec
ira Of terrestrial substances, proves the ex-
istence in the fiery envelopes of these bod
les Of incandescent clouds of metallic va
pors. Lead. iron, gold. copper and other
metals are there present.
Composition of the Sun.
The nebular hypothesis Of Laplace pub
lished in 1866 had declared that the sun
and all the planets were but condensations
from a single vast nebula that once filed
all space. The spectroscope proves that
the stars, the sun and the earth are made
up of the same elements. If the earth were
to be raised to the temperature of the sun
1t would be like tia miniature sun. The
sun Is, in fact, star. The stars are, in
general, composed of terrestrial elements
This great generalization strengthens the
nebular hypothesis in its larger accepta-
tons, but the century has brought forward
many doubts as to its minor details. With
the discovery of the spectroscope the
science of astronomical physics was born.
The most amazing single result of spec
troscopic observation is the determination
of the velocity with which stars are ap-
preaching to or receding from the earth
All stars are in motion with respect to
the earth. AS they move away from or
is altered by their velocity, precisely as the
pitch of the bell of a passing locomotive
engine is altered by its motion toward US
or from us. The motion of the sun and of
in space can be determined in this fash
ion. We are approaching some stars; we
are receding from others. The line of the
motion of our whole solar system can thus
be drawn in the universe and this problem
is now being worked out in all its details at
several places, notably at the Lick observ-
atory.
In the foregoing paragraphs it has not
been possible to note more than a few Of
the greater achievements of the astronomy
of the century. Only few of the greater
men are named. A full account of astro-
nomical progress would require a volume,
and 1t would include a host of honored
names. In each and every department we
should find Americans in the highest places
Nowhere has astronomy fourished better
than upon our own soil, and we may look
forward to the next century with conf
dence.