Evening star., 1896-01-04

lnl) ana LtO, al the eaSt-tne iatteF only
partly risen, and overhead Auriga. Taurus.
Aries, Perseus Andromeda and Cassiopeia.
With the aid of the accompanying 'plan-
isrhere' these consultations should all be
located readily and their brighter stars
should easily be identified.
For those who may not be familiar with
the use of a planisphere 1t may be well to
explain that this chart represents the entire
visible half of the heavens; that is to say,
it represents on a fiat surface the half of
the celestial sphere which is above the hori-
zon at the hour named, it's circumference
being the horizon, its center the zenith, or
the point directly overhead. The best way of
using such chart is to hold 1t nearly over
head and imagine that you are looking at the
actual heavens, having due regard to the
points of the compass as indicated by the
marginal letters. When the chart is held
In this way these points will all come right
and the stars will all fall into their proper
places The point on the circumference of
the chart which corresponds with the point
In the horizon which the observer Is sup
most.
While we are upon the subject of the
chart 1t may be well to direct attention
to the lines upon 1t, which represent the i'm
aglnary celestial equator and the paths of
the sun and the moon These lines are all
halves of great circles of the heavens, their
complementary portions being below the
horizon. 1t Will be seen that the equator
spans the heavens from the exact eastern
to the exact western point of the horizon
passing very close to the uppermost star i'm
the belt of Orion and about three degrees
the length Of that belt-below the star Mem
kar. In the head of Cetus. Bearing these
points In mind, one can easily locate 1t in
the heavens. This great circle is the line in
which the plane of. the earth's equator, ex-
tended indefinitely cuts the starry sphere
and it lies exactly midway between the two
celestial poles. The distance of the celestial
equator from the zenith, reckoned in de-
grees, Is always equal to the altitude of the
visible pole and is the same as the terres-
trial latitude of the Observers station.
Paths Of the Sun and Moon,
The SUNS PATH" known among astrono
mers as the "ecliptic," crosses the celestial
equator (the "equinoctiar0 at two diamet-
rically opposite points, known as the .'euui-
noxes." one of which, the vernal equinox, is
shown on the chart. Observe that this cross
Ing point is very nearly in line with the more
easterly stars of the Square of Pegasus, at
distance from the lower of the two little
gTeater tnan their distance apart. From
this point the line runs eastward between
the Pletades and the star Aldebaran about
five degrees south of the Twins, close to the
planet Jupiter and still closer to the star
Regulus, striking the horizon at a point
north Of east. The ecliptic runs along the
center of the zodiac" q belt of twelve con-
stellations or signs" through which the
sun successfully passes in the course Of his
The six signs which are now above the hori
zon at y O'Clock are marked on the chart
with their familiar hieroglyphic symbols.
me points at which the moons path
crosses that of the sun are known as its
modes. These nodes are continually shift
ing their positions, moving along the SUMS
path in direction from east to west. In
other words, the moon each month crosses
nninfd uyh
little to the west of the points at which II
crossed In the preceding month The rate
or the movement is such that each node
makes complete circuit of the heavens in
about eighteen and half years. At present
the descending" node, at which the moon
passes from the northern to the southern
side OF the suns path. is near the star Regu-
lus, as is shown on the chart The position
of the moon itself at p. m. for every day of
the month on which she is above the horizon
at that hour is marked on the chart
Among objects of especial interest this
month are the two variable stars Algol. in
Perseus, and Mira, the wonderful STAR in
the constellation Cetus. "Minima" of AleoI
convenient for observing will occur at 1 m
on the 9th; at pm on the 11th; at m on
the 14th; at II pm. on the 31st The pecu-
liarity Of this star Is that after shining for
about two and half days as a star of the
second magnitude. it descends in the space
OF ABOUT four hours to the fourth magnitude,
and in the course of the next four hours re.
gains Its usual brilliancy. The explanation
is that the star has dark satellite revolv.
Ing round 1t, which, passing periodically be.
tween us and it, cuts off a portion of its
light. Algol is now, at 8 O'clock very
nearly in the zenith. 1t can be located ex
actly with the aid of the chart There is
near 1t star of the fourth magnitude, which
serves as very convenient Comparison
star" When at it's minimum AlgoI and this
star are of the same brilliancy.
Variation in Drilliancy,
Mira can be found easily by noting its
position with relation to Menkar and the
ether stars of Cetus shown on the chart.
This star has period of about eleven
months, during seven of which it is invisible
to the naked eye, being when faintest OF
between the ninth and tenth magnitudes
When shining with its greatest brilliancy
1t occs s.onally becomes the rival of Menkar
which Is star of the second magnitude but
more often it stops short of this degree of
splendor. Last year it attained to only the
fourth magnitude, and the year before to
the third. A maximum of Mira may be look
ed for in the early part Of this month. At