Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1897-02-04
SKIS N EEBR0ARY.
Position of Planets-Their Rotations and
Revolutions - Difficulty OF Determining
Axlul RDtation-Eixed stars.

INV HuOH VIII puhB luTOuPn tue lOItpN-
lug phasos: First quarter on the 9th.
full on the 18th. last quarter on thu
Odd. On the Sth she will he in apogee
and on the goth in perigee. The sun
will DO degrees A minutes AZ seconds
on the last OF the month. trayersing an
arc of 0 degrees IL minutes and 10
seconds during tho % days of the
month an arc half as largo again as
that passed through in course of the
past month.
During the earlier portion of the
month Of February the planet Mercury
is in Sagittarius, but enters Aquarius
before the middle Of the month, where
it will linger during tho remainder Of
1t. Venus will remain in Aquarius
for some time, but pass into Pisces
before the month is half over No ono
who casts his oye up to the evening
sky will mistake the planet for any
other, for it shines with that Intrinsic
brilliancy that renders Venus the eveu-
ing or the moruing star par excellence.
We often and quite correctly speak OF
other visible planets as morning or
evening stars, but in ancient and even
later times these two namos were eX-
clusireIy restricted TO Venus, tine an
clients calling her iIesperus whom even
ing star and Phosphorcus when morn.
ing star. 1t eau never be more distant
from the sun, or, to use a technical ex
preston. it's elongation, which may be
either east or wesr can never be greater
than about AZ degrees 80 minutes This
most eastern elongation it will reach on
the 10th OF the month.
The greatest brightness, however,
which Venus can attain IS neither
when it is nearest the earth, for then it
presents too small phase, nor when it
10 at the maximum elongation, but
whom 1t is at an elonaation Of SO degrees
from the sun. The reason for this fact
is the result of problem into which it
would be out OF place to enter hero.
The solution of this problem acquires
both greater knowledge Of mathe.
MATES than we can nationally suppose
the average reader to possess and some
familiarity with the laws of optics.
Mars is in Taurus and forms with
Capelia and Aldebaran very obtuse
triangle with the planet at the obfuse
angle. 1t 10 also very brilliant and
particularly conspicuous by its red
color which will prevent ii from being
confounded with any other planet or
star. Mars will be on the meridian at
about 7.30 O'Clock on the It'll OF the
month.
Jupiter is in Leo and rises coon after
O'Clock in the evening, SO thatfrom
o'clock this great planet will DO a
very prominent Object in the eastern
sky, Inferior in brilltancy only TO
Venus. Saturn is In Scorpio and rises
n little before o. .lock in the morning.
1t may he seen by personB who rise
before ths morning sun, In its superior
effulgence. eclipses all other celestial
lights. Like the earth, all other plansts
and satellites partase OF two notions.
one about the axis, the other about tho
sun, and in the cnso Of the satellites
about their primary. This time of one
complete revolution Of planet about
the sun is its sidereal period to be dis
tinguiahed from the synodic period,
which is the time elapsing betwesn two
successive coniunctiuns or oppositions.
This syuodic period can be determined
without any special difficulty. and,
having found 1t, the sidereai period ia
an easy problem, a
or all tho planets Mars has the
longest synotlicai period, which amounts
to very nearly $50 days: then follows
Venus With noarly IS! days, and tho
series ends with Mercury. having a
period Of but ll6 days.
To find thu time of q complete
| rotation of planet ia quite subtle
problem, and if it tan be determined
at oil il In generally found by observing
spots on the piauets disk visible in the
telescope as they cross the disk. 10
| find tho times Of tho axial rotation Of
Mercury, the asteroids, Uranus and
Neptune has as yet haiiled all the skill
of astronomers OF tho planets tho
times OF whose axial rotation is known
it is again Mars that enjoys tho privi-
| lege of having the longest time at rota
ton, then comes tho Earth and after it
Venus. In spite of its tremendous bull;
Jupiter rotatoa on its axis in shorter
time, viz: nine hours, than any other.
Saturn. the next in size, moves once
abnut its axis in about 1911 hours
II seems strange that the two largest
OF tho planets, whose bulks SO very
much snrpass those of the other mem
berg Of he solar system, should have
tho quickeHt motion about their axis.
Tho magnitude OF II planetary body,
however, has nothing to do with tho
rate of rotary motion. Tho reader will
recoIlect that such diminutiye body
as our moon performs one circuit
around its axis in more than 2I days
which is only about two days longer
than the time in which tho colossal
body of the sun turns once on its axis.
OF the principal considerations visible
during the earlier hours of the Fuhru-
AIRY evenings Gemini and the Two
Dogs will DO on the meridian about 0
O'Clock, while Amiga, Taurus, Orion
and Lupus are bending toward The
western horizon, though not yet being
very distinct from their meridianal
position.
Tho constellation Gemini, or tho
J Twins, ia distinguished and easily
recognized by two bright stars, Pollux
and Castor, or Beta and Alpha, the
former of the first and the latter Of tho
saconu magnitude Though Castor now
| yields in brightness to hqllux, il has a
special interest in that it is double
star, tim dupicity of which can with
| out difficulty he detected by means OF
a small telescope. Tho ancient Greeks,
with their profound pc Hef of imagina.
| ton and Keen sense oil the picturesque,
saw in this constellation tina two twin
brothers OF whom thnre exist SO many
legends in ancient mythology. South
| OF Gemini ia situated the Canis Minor.
or tho Little Dog marked by tho frat
magnitude star Prccyon, Crock word
signifying "beforo the dog" since it
rises about half an hour before s,irius,
the Dog star. Not far from Procyon we
SEQ tbs next brightest star in this son.