Evening star. [volume] (Washington, D.C.) 1854-1972, 1902-05-31
THE HEAVENS IN JUNE
The Brightest Star in the
Northern Hemisphere.
SHIFTING EQUINOXES
AN IMPORTANT BEARING IN
MODERN ASTRONOMY.
zodiacal Consultations - Making the
Heavenly Bodies Serve as a
Timekeeper.


Written for The Evening Star.
The brilliant orange yellow star which
may now be seen at 8 pm. nearly over
head, we face the south, is Arcturus
usually accounted the brightest star in the
northern hemisphere. 1t can always be
identified readily when above the horizon
from its position on a continuation of the
curve of the handle of the Great Dipper.
| Following this curve still farther We
strike, at a distance from Arcturus about
equal to its distance from the end star in
the handle of the Dipper, Spica, in the con-
stellation Virgo In the west. at one-third
of the distance from horizon TO zenith,
stands Regulus, the principal star In Leo
and the jewel in the handle of the Sickle,
which forms the Lions head and Shout
ders.
At about the same altitude, between east
and northeast, is Vega, or Alpha Lyrae
one of the two rivals of Arcturus in bril-
! liancy. The rudy star seen low in the
southeast is Antares, the Heart of the
Scorpion. Three other stars of the first
magnitude are above the horizon at the
hour named, though too low to be visible
| Capella, just setting between north and
northwest; Affair, just risen in the east
and Pollux. the more southerly of the
Twins tGeminD, now some six or eight de-
greeS high in the northwest.
| The Constellation Virgo.
| This constellation can easily be located
| by means of the star Spfca, which repre-
| sents the wheat-ear supposed to be car
| ried by the Maiden in her left hand. To
| trace its outlines is, however, not so easy
a matter. Virgo is, in fact, one of those
mystifying consultations. of which the
| origin is lost in an antiquity so remote that
| their rationale is no longer recoverable.
! The constellation certainly did not origi-
i nate, as many of the consultations I'M
doubtedly did, in anything suggestive in the
! grouping of its stars Indeed. so vaguely
! defined We're its limits in the time of
! Ptolemy that this astronomer did not hest
tate to remodel it in order to give the fig
ure better proportions"
The most striking portion of the con-
stellatton is a Y-shaped figure, the base of
which is formed by the star Spica while
| the arms of the Y-possibly the original
| wings of the Maiden-are formed by five
| stars, one arm extending eastward toward
| the star Regulus and the other extending
| toward the north. The central one of these
| five stars, and the central star of the figure,
| is Gamma Virgins of the third magnitude.
| 1t is exceedingly beautiful double star.
| receivable with a small telescope, and,
| moreover, is binary star. That is to
say, its components. both white, and are
| of nearly equal brightness are revolving
| about theis common center of gravity, the
| period of the revolution being about $50
years. Gamma Virgins stands in the list
| OIL the IlTSl Oh THESE very interesting stellar
systems to be discovered, by the elder
| Herschel. another in the same list being
| Castor, the more northerly of the Twins,
the period of which is thought to be about
| 1000 years.
The Shifting Equinoxes.
Virgo is one of the zodiacal constena-
| lions. the sixth, reckoned from Aries, but
| the seventh if we reckon from the present
position of the vernal equinox a the west
ern border Of the constellation Pisces. 1t
occupies the place Of the sign Libra,
| which the sun enters annually about the
Dist of September. The autumnal equinox
| the point at which the sun crosses the
| celestial equator in passing, on the date
| just given, from the northern to the south
| ern hemisphere--is at about two-fifths of
| the distance from Spica to Regulus, almost
exactly on straight line drawn from one
! to the other of these two stars.
| In the time of Hipparchus in the second
century B. c., Spica was in the northern
| hemisphere. 1t is now in the southern, be-
| ing a trihe over 10 degrees south OF the
equinoctial or celestial equator. The change
| has been brought about, not by any change
| in the stars position with reference to the
| surrounding stars. for the positions of all
the stars have been similarly affected, but
by change in the location of the line
which separates the two hemispheres. The
celestial equator is the great circle in
which the plane of the earth'S equator in
| definitely extended On all sides cuts the
L
| nual Passage round the has a slight
| gyratory motion which may be likened to
| the wabbling of a spinning top, the plane
of its equator and consequently the line in
which this plane cuts the celestial sphere
are continually changing their positions
| The two points at which the celestial equa-
| tor and the ecliptic, suns path, cross
| each other are slipping westward, a. a rate
| which in the last 1900 years has changed
| their position among the stars some 80
| degrees-the length of a zodiacal Sign
| and which in the course of about 900
| years carries them entirely around the
| heavens. The discovery of this movement
\ known as the procession of the equi-
! noxes.' was one of the first grand discoy-
| cries of exact astronomy. 1t was made by
! Hipparchus. by means of this very star
| Spica. Upon comparing his own observa-
! tons with others made one hundred and
| fifty years earlier. Hipparchus found that
| this star was some two degrees farther
| east than the earlier observations had
placed it. and since it's position remained
| unaltered with respect to the surrounding
| stars 1t was evident that a change had
| taken place in the point-the equinox-from
which the measurements were taken.
| Change Affects Star Catalogues.
This continual shifting Of the equinoxes
has a very important bearing in modern
astronomy. The positions of the celestial
bodies are given in star catalogues, or laid
down upon charts, by right ascension"
| and "declination,' which correspond to