Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1899-12-07
THE SKIES IN DECEMBER.

Baltimore sun. f4lL.- Ill
The moon will have her phases during
the month of, December as follows:
New, on the ga first quarter, on the
9th; full, on the 10th, and last quarter,
on the 24th,. Shu will DO nearest the
earth on the 18th and farthest of on the
I'D. While at the beginning of the
month the sun will be ] degree 81
minutes from the southern limit of his
motion in declination, he will reach
that limit on the 22d of the month at
7.55 p. M, at which precise moment
the winter season begins. At tho he-
ginning of the month the hourly varia-
tion of the SUMS declination is about
% seconds, while on the day previous
to the winter solstice it Is only about
half second, proving the SLOW ness OF
the suns motion near the solstices.
Its motion in right ascension, however,
is faster at the solstices than at the
equinoxes, which clearly follow from
the fact that the path of the suns
motion is inclined sto the equator, and
hence the motion in declination tends
to paralelism, and IS consequently
slow, and to jEerpendioularity at the
equinoxes, and Is, therefore, quick,
while in regard TO the motion IN right
ascension the case is obviously re-
versed,
The planet Mercury is at first In
Sagittarius, about the middle of the
month in Scorpio, but toward the end
back in Sagittarius, on account OF ITS
apparent retrograde motion. The
| apparent motion of the planets among
the stars cannot but be somewhat per-
picking to any person who lacks the
power of realizing tho motion OF body
| pt fraK rFa hrd NIntpnd
from the sun, all the planets would be
seen to advance in the same direction,
viz, from west to east, in planes hut
slightly inclined to each other, but
with unequal velocities, and such a
thing as retrograde motion could net
take place. Seen, however, from the
earth, body that is itself In motion,
the motions Of the planets around the
sun appear in an entirely different
manner. Surprising two bodies to
move in the same direction at different
rates, it is easy to see and is common
experience that the slower of the
bodies, as seen from the swifter, would
appear to move In the opposite
direction. When planet appears to
move in the direction in which the sun
appears to move in the ecliptic, its
apparent motion is said to be direct,
while, when it appears to move in the
contrary direction, 1t is said to be
retrogi ade. The apparent motion of mn
inferior planet is always direct, except
within a certain elongation east and
west of the inferior conjunction, when it
is retrograde. The apparent motion of
superior planet that is, one whose
orbit envelopes that Of the earth--is
similar to that of an inferior planet,
| hnt In, M Lad tho
retrogression takes place near inferior
coniunction, and ip the former near
opposition.
Venus will be al first In Sagittarius
and later on In Capricornus. She is
at present too near the sun to be seen
long in the evening, and then only in
the evening twilight. She will set
about o'clock in the evening and We
may catch glimpse of her when she is
close to the horizon. Venus began
shining as an, evening star at the latter
part of November. and will act in this
capacity until next August Mars keeps
near Venus and will set nearly half an
hour earlier than the latter planet, so
that he is in an unfavorable position
for observation, neither acting as
morning nor evening star. Jupiter is
in Scorpio, and will act ns morning
star. During the first portion Of the
month the great planet rises between
and O'Clock. and during the latter
between and 8 O'Clock, so that an
early riser will see this beautiful planet
in the eastern portion of the sky,
heralding the coming Of the king of
day. Saturn is the third of the planets
that are in the constellation Sagit-
tarius, but as it sets before 8 o'clock
| tho nj 10 lilo Mnr ~
an unfavolaple position for obsei va
tion. On the 18th of the month il will
be- in conjunction with the sun and
totally invisible, except, of course,
through large telescope. The
planetary aspect Of the sky during
the December evenings is consequently
no fine one, while the morning skies
will be adorned by the presence of
Jupiter.
In the course OF the month two
eolirses will occur, an annular eclipse
of the sun ON the I'd, not visible in
this latitude, and partial eclipse of
the moon on the 10th, which will be
visible here. Nearly the whole Fart of
the lunar disk will be eclipsed The
beginning Of TIE eclipse will be a
quarter of In the evening, and end
about Z minutes after 10.
Comets, although deprived of their
threatening character, which they en-
ioyed for so many ages, are still of in
tense interest both by rarity of their
appearance and by certain mystery
that still adheres to them. 1t is not
our intention in this article to enter
into ullIdescription Of these singular
bodies, but only to touch upon some OF
their peculiarities. From the enormous
space they occupy in the sky oGe would
feel inclined TO conclude that their
mass must be very large. It is but too
common mistake not to discriminate
sufficiently between volume and mass.
The latter depends altogether upon the
density of the substance. The sun, for
instance, is about one and one fourth
million times as large as the earth,
while its mass is only about one third
OF million times as large as the earth s..
Although our knowledge of the masses
OF comets is as yet far from accurate
and so far merely speculative, there is
no doubt that the mass of comet
compared with its volume is quite
insignificant. We may infer from the
fact that comets have frequently an.
preached the earth and other planets
so closely as almost, il not altogether,
to come into actual contact with them
without, as far as observations 90,
having ever produced the slightest
effect upon the motions of the planets
and our earth, although the effect the
latter produced upon the comets was
great enough to change their orbits.
1t follows from this as a very interest
ing fact that the density of comets
must be smaller than that of anything
. | xua hor