The times. [volume] (Richmond, Va.) 1890-1903, 1901-12-29
STARS IN JANUARY
INVITING STUDY
Sun Reached Its Southernmost Lint
and Now Marches North.
POLE STAR NOT TRUE MARKER
It is Getting Nearer the True Pole, and VIII
Be Ia Hail Degree of ii by The Next
Century-SpIendid Consultations
Plain TO the Naked Eye.
POLE STAR NOT TRUE MARKER
written for The Sunday Times.)

On December Dist the sun reached its
it has been very slowly but continually
moving northward again. The sun has
a two-fold motion, which, of course, is
only apparent, for its apparent diurnal
motion is owing to the actual rotation
of the earth on its axis. and its apparent
annual motion is due to the revolution OF
the earth about the sun in the place OF
the ccliptic which is inclined to the plane
of the equator at an angle of twenty
three degrees and twenty-seven minutes,
called the obliquity of the elliptic The
latter undergoes a very slight but con-
tinuous change until it will reach its min
imum, no less than 900 years hence.
when it will be twenty-five degrees and
fifteen minutes After having obtained
this minimum it will begin to increase
again. The fact that calculations can be
made involving such minute changes
within an enormous period OF time fur-
nishes a splendid testimony to the Won
derful power of mathematical analysis
and the ingenuity of man in applying 1t
TO the grandest science that has ever
been devised by man. The motion Of the
earth around the great luminary, the
sun, is not uniform, for it is performed,
not in a circle but III an elongated curve,
the ellpse in one of the two foci of
which the sun is situated. by whose at
tractiVe power this motion is generated
But even if the earth's motion in the
plane of the ecliptic were circular ana
uniform, the apparent motion of the sun
north ana south of the equator, or, to
, use a technical phrase in declinatlon
would still be variable. for meridians that
divide the ecliptic into equal parts DO
not divide the equator into such.
The reader not wholly unacqualnted
with spherical geometry will readily I'M
derstand the reason for this. In conse-
quence Of the unequal motion of The sun
in declination 1t will move at certain
times faster or more slowly than at otner
times. Near the equator the sun moves
fast whereas near the points OF Its north
nrnmost and southernmost limits II
moves very slowly: nay, at these limits
themselves it seems TO stand still Tor
time for which reason these limits are
called sols:ices, from the Latin meaning
the standing still of the sun.
The motion of the sun in destination is
Of the highest Importance, as the seasons
of the year and the shifting of the points
OF the suns rising and setting depends
upon it. In this oblique motion of the
sun with reference to the equator must
also be distinguished its motion in right
ascension from that in declinaton, the
former being along, or rather parallel TO
7he equator. This motion is necessarily
variable. too. The angle which the dur
nal paths of the sun and the stars make:
with the horizon depends altogether upon
the latitude of the place OF observation.
At the equator, for, instance; The diurnal
circles of the sun and stars cut the hori-
zon at a right angle, whereas. at the
poles they move parallel to the horizon,
which. in this case, is the equator. On
ELL intermediate points the angie is
ohliuqe. its magnitude depending upon
she latitude of the place
These three positions are respectively
called the right. the parallel and the
pblicue spheres. The latitude of place
Is always equal to the elevation OF the
nearest pole above the horizon, TACT OF
the highest Importance and worthy OIL me
Earnest attention OF the reader by
means of an instrument. called the sex
tant. the manipulation of which is quite
simple, the traveller can always, with toll
prable accuracy, determine the latitude
cf the place where he happens to be,
BY Observing the angle of the pole star
from the horizon In the southern hem
3sphere the pole of which is not marked
by any star in close enough proximity.
this observation would be more difficult.
TILE POLE STAR
1t is necessary to say here that the
pole star does not exactly mark the
llNe IoiS VI Sbe iiSf'' 49, ;.;.
the whole armament makes one circuit
every day At present, it is about one
degree. fifteen seconds distant from the
true pole. Four thousand years ago IT
was at far greater distance from It,
IL we connect the brightest star in the
bowl of the Little Dipper with the last
star hut one in the handle of the Big
Dipper by a straight line and hisect it.
the point of dissection Is marked BY
sufficiently bright star in the constella-
ton Draco. called Thuban. which former
s.v WAS the pole star Orr present pole
star will approach the true pole of the
heavens within half a degree Of it. This
limit viii be reached in about n cen
fury, after which it will recede more and