Evening star., 1901-05-04

eighth month was known as the month Of
the star of the Scorpion" the tenth be-
longed to the star Of the Goat" Capri
corn), and the twelfth to the star of The
Fish of Hea" CPisces)
Two of the stars of Virgo are of especial
interest-Spica and Gamma 1t was from
observations of the first OF these two stars
that Hipparchus, the father of mathemati-
cal astronomy, who fourished in the second
century, b. G.. discovered the movement
known as the Procession of the Eaui-
noSes, that is to say, the fact that the two
points at which the sun crosses the celcs-
tial equator in passing from one hemis-
phere to the other are not fixed. but are
slowly sliding along the ecliptic. in dlrec-
tion from east to west. The movement is
caused by a slow gyratory motion of the
earth. as 1t spins on its axis, I'm consequence
OF which the plane of its equator and there
fore the great circle in which this plane
cuts the starry sphere-the celestial equa-
tor-are subject TO a continual change. The
eciiptic remains fixed in its position among
the stars, but the celestial equator is con-
tinually swayng from it's position, the
movement taking place at a rate such that
the two crossing points perform complete
revolution Of the heavens i'm about 25s"
years. In the time of HiPparchus Splca
was in the northern hemisphere: it is now,
in consequence of this shift Of the equator,
in the southern hemisphere.
Gamma Virgins is beautiful double
star, with components of about equal
brightness, easily separable with a small
telescope 1t is also a binary" star, that
is to say, its two componentS are hound to-
gether by mutual attraction and revolVe
about one another or rather about their
common center of gravity. IL iS one or the
first of the binary stars discovered. by Sir
William Herschel, about the beginning Of
the last century. Another binary in Her
schelS first list is the star Castor. the more
northerly OF the twins (ieminD. now to be
seen at the hour of our observation, low IN
the west. The period of Gamma Virgins Is
about l75 years; that of Castor is supposed
to be about 900 years.
The Planets.
Mercury VIII he morning star, but iu-
visible until May, IL. and after that date
an evening star. 1t viii not be visible
such, however, until about June l.
Venus has been an evening star since
April 80, but throughout this month she
will be too close to the sun to he visible to
the naked eye.
Mars continues to be an interesting even
ing star, in Leo, its weii-known ruddy light
contrasting strongly with the paler yellow
light of Regulus. near which star II now
is. On April > Mars was stationary, at a
Point about eight degrees northwest or
Regulus Since that date IT has moved
eastward taking a downward curve, which
has brought it nearer to Regulus. BY the
close Of the month II will be about ten de-
grees to the east of that star
Jupiter in Sagittartus, has become an
evening star. rising on the first OF this
month at about IL o'clock pm. Saturn.
also an evening star, In the same constel-
lation, rises half hour later Uranus is
an evening star, about ten degrees north
east Of Antares. In the Scorpion, rising an
hour and a half before Jupiter. All three
ot these planets run low to be un-
favorably situated for telescope observa-
tion in the northern hemisphere.