Evening star. [volume] (Washington, D.C.) 1854-1972, 1896-10-03

Arcturus, although the latter star is usu-
ally regarded as the brilliant of the north
ern skies. All three of these stars s1rpass
In splen6or considerably an average star
of the first magnitude To decide upon
their respective claims to the leadership in
this respect is not easy, owing to their
difference in color. Capella is yellow, Arc
turus is inclined to orange, while Vega is
tluish-white.
Every one is aware that the stars are
classed. according to their brilliancy. into
magDitudes. the first six classes embracing
all the stars that are visible to the naked
eye. AS the magnitudes are now usually
reckoned, there are twenty stars of the first
magnitude, of which only fourteen are
ever visible &c observer in the mean
latitude of the United States-fO degrees
the remaining six being among the south
Circumpolar stars, which never appear
above our horizon About sixty are of the
second magnitude, two hundred of the
third, four hundred and fifty OF the fourth
eleven hundred of the fifth and four thouS-
and of the sixth. These numbers, except
the first. are only approximate. the figures
being given variously by different authori-
ties. 1t thus appears that The whole num-
Der of the stars visible to The naked eye
Is under six thousand. of which two-thirds
SO faint that they can lie seen only on
the clearest nights. The telescope magni-
tubes run down to the sixteenth or seven
teenth. which last embraces the faintest
stars revealed by the largest telescopes or
by photogI apply
This classification is, of course, purely
artificial There is no natural arrangement
of the stars in respect to briliancy, but, on
the contrary, they are of almost every de-
gree of brightness, from the brilliant Dog
star down to the tinieSt sIeck of star dust
that makes its appearance on a photo
graphic plate. The plan was hit upon orig
inally simply as convenient means of in
dicating roughly in catalogues a stars
brightness. and as 1t was carried out by
the earlier astronomers there was very
little system about it. Astronomers were
TO the magnitudes." even of the naked
eye stars. and in the cases of the telescope
stars their estimates were often two or
n ore magnitudeS apart. OF late years, how
ever. attempts have been made to introduce
some system into this classification and to
place the mea surement of star magnitudes,
o. photometry. as this branch of astronomy
is called, upon scientific basis
Naked Eye Stars.
1t has been agreed that the classes shall
be so formed that a typical or average
star Of one magnitude shall be two and a
half times as bright one of the class
next below it. This ratio has been adopted
partly because 1t leaves the masnitudes OF
the naked-eye stars. as formerly reckoned
practically unchanged. and partly for the
Still better reason that average star OF
the first magnitude is thus rendered exact
" one hundred times as bright star OF
the sixth. Furthermore. the magnitudes
are now subdivided into tenths and eve,
hundredthS and are expressed decimally
Thus. q star which is midway in point OF
brightness between an average first and ar
average second magnitude star Is said tC
be of magnitude Is star of which the
magnitude Is IA or 1.5 is nearer the frs
than the second magnitude: If It's magni
tude is 1-6 10 is 1t Is above the average
OF the second magnitude, but Is not br.gh
enough to be reckoned as a first magnitude
star.
This photometric system can be rendered
more clear by means of a few examples Sc
lected from the stars which visible to
night. The magnitudes are those given ir
the American Ephemeris
Aldebaran. the Bulls Eye" which l:
now Just above the horizon. little nortl
Of east. is typical star of the first magni
tude. Fomalhaut. in the Southern Fish
now to be seen low in the south. is of mag
nitude 1.3. mat is. it Is three-tenths of
magnitude below the standard of the class
to which it belongs. Affair. in the Eagle
now in mIiheave1s in the southwest Is
E. little brighter than AldeSaran. its magni
tude being 90. Vega is CT magnitude o.
that Is. 1t is eigLt-tenths of a magnitud
brighter than Aideharan. while Capella i
nearly full magnitude brighter than tina
star. its magnitude being OIL.
AS typical second ma gnitude stars w
may take Beta Aurigae, the star in tn
right shoulder of Auriga. and Dubhe. til
upper OF the two pointers in the Grea
Dipper. The five stars which form til
w" of Cassiopeia are us ually regarded q
Of the second magnitude. but all of ther
are considerably below the average bright
ness of stars of this class. TIE brightes
two are Alpha and Gamma. the second an
third. Teckoned downward. as the group
now posed These are beth of magnitud
2.3. OF the stars OF the Swan or No-the.
Cross. Deneb. in the tail of the Swan-th
head of the Cross-is the brightest. Ii
magnitude is Ia. That is. 1t is nearer tn
first than the second magn. tude. Beta. 1
the Beak of the Swan. is of magnitude 3
or about midway between the second an
third magnitudes. The Pole Star is G
magnitude ID, ard Is. therefore. not fu
second-magnitude star
Sword of rcrseus.
The principal consultations now abov
the horizon at D pm. should all be foun