The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1892-12-03
COMETS.


As these cratic inhabitants Of the celes-
tial world are at all times of their appear
ance the objects of great interest to the
inhabitants of our planet, it will prove OF
interest to many to give brief description
of their habits as far as We are personally
familiar with the sane.
The word comet is derived from the
,;rcek KoD,e a hair title which has its
origin IN the hairy appearance often exhio-
tied by the haze or luminous vapor. the
D,..sence of which Is at first sight the most
striking characteristic of the celestial bod
les called by this name. The general iea-
tnres of a comet are A definite point or
nucleus. ncbulous light surrounding the
nucleus aud Il luminous train preceding or
following the nucleus In ancient times
when the train preceded the nucleus-as
is the ease when comet has pa. Sed ITS
peribclioa and rccedes from the sun-it was
called the beard. being only termed the tail
when seen following the nucleus as the sun
approached. This distinction has dlsaP-
pcarcd from all modern ASTRONOMICAL works,
and the latter name is given 10 the append
.tgc. whatever liz apparent position.
Neither this luminous attendant, the tan
nor the nucleus is now considered AN esscn-
tial cometary element, but all bodies are
classcd a. comets which have a motion oil
their own and describe orbits Of an ex-
tremely elongated form. Astronomers IN
form us that there are several PLAIN points
of difference between comets and planets.
The planets move in the same direction,
from west 10 east. which in astronomy Is
termed direct motion. but the movements
Of comets are often from east to west, or
rctrograde. The orbits of all the planets
are plainly defined and confined to a zone
of no great breadth on either side of the
ecliptic. but the paths Of the comets cut
the ecliptic in every direction. some being
nearly perpendicular with it.
The Orbits of all the planets are nearly
circular. or more properly speaking. are
ellipses of very small eccentricity. The
orbits of comets. on the other hand, present
every variety Of eccentricity, some of them
being ellipses OF elongated closed orbits OF
Warious degrees Of elongation. Others hyper
bolas. while the majority have Il form OF
nsbit not differing sensibly from the para
frols, which is the limiting form OF curve
ia which both the ellipse and hyperhola
approach under given conditions.
The disc"very that comets are celestial
bodies. cxtraneous u Dur atmosphere, Is
due to Tycho Brahe, wh" sscertained the
fact by observations of the comet 81 l3ol,
Newton succeeded in demonstrating tiiat
they are Guided in their movements by the
-slaIe principle which controls the planets
IN their orbits. HALEY was the first 10y
determining the parabolic elements OF a
number of comets from recorded obServa-
tions. To identify the comet Of 1867 with
,one which had been observed in 1907 and
she observations recorded by kep!er and
l,ongnmontanus. and also with a comet
observed in 1871 by Apian, at lngolstadt.
and thus eonfidentaily to predict the return.
at the end of 1873 or beginning of lI59,
of comet which WOuld have the same
aarabolic elements.
The treat comet of $50. which furnished
Newton with the occasion for proving that
comets revOlve around the sun in comic
sections and that, consequently. they are
retained in their orbits by the same force
az that which regulates the movements of
the planets, appears to have been about
the most remarkable one up to the present
era. for brilliancy of any of which we have
any authentic accounts This comet is
supposed to he identical with the one that
apneared about the time of Caesars death
"A Is. c.: with that which was seen in
the reign of Justinian in the year J3l and
with another in the year l06. in the reign
81 Henry ii, the period OF revolution,
according to the orbit calculated for it by
Winston, being about SO years. This
comet approached nearer to the sun than
any known, except the one of 1913, the
calculation of whose perihelion distance,
from the scarcity of observations, has little
certainty. The great comet Of 1850 APP
preached the suu within the 1899 of the
semi-diametcr of the carth's orbit.
The tail of comet is nearly always
away from the sun, frequently assuming a
curved form. 1t increases in length with
its proximity to the sun, but does not
acquire its greatest length till after passing
istics of comets in genera, aad were exem-
plified by the one of 1850 in remarkable
degree The argument is advanced by
some that the train or tail of the comet is
caused by vaporization, produced by the
intense heat to which the body of the GOMEZ
is exposed in its approach to the sun.
In the present century the comets mos
remarkable for their brilliancy were those
az the years 1911, 1913, 1858 and 1882
.Spectroscopic investigation, so far as il
has been pursued, points to the conclusion
that the nucleus is selfluminous, but thai
The tail shines with reflected light. 1t ba
been recent discovery, in determining TIN
tracks of those streams of dark bodies tina
cause meieoric showers, that some of thu
tracks coincide with the orbits Of wei
known comets From this we may infe
that star showers and comets may be onl,
different manifestations of the same thing
PiIaesrilie, Nd.
ri. ....oofnl nalrnoffo that orowS :,