The Birmingham age-herald. [volume] (Birmingham, Ala.) 1902-1950, 1923-04-08
Starry Skies As
Seen During April
BY PROFESSOR BARTON

In our discussions of the stars we
have given little attention to the star
which Is to us by far the nearest
brightest, most interesting and most
useful of all.
The night has a thousand eyes,
And the day but one.
Yet the light of the bright world dies
With the dying sum-"
| The day star" is after all a star
Besides it in the sky even In midday
are 1000 other stars sufficiently
bright to be seen with the naked eye
if the sun were blotted out and the
| brightest ones may be seen in tele
scopes and even seen without tele-
scopes where the suns light is cut
off as at the bottom of a we'll In
high attitudes they may be photo
graphed. True the sun appars to us
somewhat different from the stars,
but little reflection conyinces that
the differences are merely due to the
fact that we are so much nearer to
it than to the other stars. The sun
has its retinue of eight planets re
volving about 1t, the earth, third in
order at a distance of only $4,000, 600
miles. No wonder the sun appears
! large and bright to us. AS one re-
cedes from the sun it's apparent di-
ameter decreases inversely as the dis
lance we travel and the brightness
| inverSely as the square of the dis
tance. In Figure 2, the relative sizes
of the sun as seen from the various
! planets of its system are shown.
From the outermost planet. Neptune,
! the suns disc would be so small that
1T could not be seen with the naked
eye, and it would appear as an in
tensely brilliant star. Only a little
| optical assistance would be required
to show a small disc.
The next nearest star to us which
is known is Alpha Centauri, which is
| 215.000 times as far from us as the
sun. The disc of the sun as seen
ameter of only from three to four
thousandths of a second. No tele-
scope is powerful enough to detect
a disc as small as this. AS seen
| from that star the sun would appear
1 is a little brighter than this, which
! just as the star Arcturus at A, Fig
ure l. does to us. Alpha Centuari
! indicates that 1t Is little brighter
than the sun. We cannot see this
star here. The nearest star visible
/ TO the naked eye here is Sirius, at
/ b. Figure /. 1t is about $4,000
times as far as the sun. From Sirius
the sun would appear as a star of
| the brightness of Nath, the star at
| c, Figure /. The sun gives 11,000.-
/ 100000 times as much light as Sirius.
/ IouL IL sirius were at the same GlS-
/ lance as the sun 1T would be % times
as bright as the sun. The star at
/ ID in the same constellation, if
| brought to the same distance as the
sun would be 1000 times as bright
and the middle star of the belt of
! Orion, 10000 times as bright. Rigel,
at L, is believed to be $4,000 times
as bright as the sun, and is probably
the brightest star known. although
the recently discovered spectroscopic
binary gives a combined light about
as great. Vega, at F, Capelia, at G
and Arcturus at A appear of almost
equal brightness. They are about
100, 60 and 40 times a. bright as the
sun, respectively.
Which stars are of the same
brightness as the sun may be ask ed,
since these are SO much brighter. We
have stated that one of the stars of
the double star Alpha Centauri is of
the same brightness as the sun. This
star cannot be seen here. All of the
first magnitude stars seen here are
brighter than the sun. Procyon, at
Fl, is about seven times as bright.
The others are still brighter. Is the
sun, then, SO faint as compared with
other stars? This does not follow.
a bright star, like the city on a hill,
cannot be hid. A star which appears
bright to us may be bright because
it is itself very bright, even though
distant, as in the case of Rigel, or
because near us, even though intrin
sically less brilliant. as in the case
! OF Procyon. If l select the brighter
stars ! do not necessarily include all
the stars bright of themselves, for
some may be very far away, and. in
fact, Deneb. in Cygnus. and Campus,
not visible here. are quite bright, but
so TAR away that we have been I'M
able to determine their distances.
Nor are all the bright stars neces-
sarily large. The sun itself illus
trates this case. If brilliance is =
reason why stars may be bright to
us. then we may expect that the
trinsic brilliance. We find that the
rst-magntude stars-there are
about 20 of them-average about 200
times as bright as the sun.
If there are bodies much less bril-
liant than the sun we would natur-
ally expect to find them among the
fainter stars. in greater numbers,
than among the brighter classes. If
the sun were removed to the average
distance of the first-magnitude stars
II would appear as a star of 6.S mag
nitude, nearly whole magnitude
FAINTER than we can see with the
naked eye. AT the average distance
or the faintest stars visible to the
naked eye it is of SO magnitude.
The star which we see with the
naked eye averages considerably
brighter than the sun. Distance nat
uraily prevents us from seeing dis
tant small bodies or bodies faint in
themselves. The faintest star which
has been found is the companion to
the star Procyon at II. This COM
panion is OF magnitude Is and very
difficult to see. 1t gives out only
six one hundred thousandths as much
light as our sun. An eleventh.
Wi,
double Alpha Centauri is of the
same brightness. There are probably
stars still fainter. some which are
| dead bodies, like planets, which give
out no light of themselves, and are
| wholly invisible. or the luminous
| bodies the sun seems to be of about
| the average brillance.
Inc brightness alone, Of course,
| gives no good evidence of the size
| of the bodies. The very hot stars OF
the same size are probably brighter
and the cooler ones fainter. The sun
| is of intermediate temperature. The
sun is $4,000 miles in diameter. The
| diameters OF other stars are, in most
cases, not known or at least only
indirectly and with considerable
degree of uncertainty.
Planetary Occulations.
| During the month the Planet Jupi-
| ter will pass between us and two
"a nj stars. On the morning of April
3, at 3 a. m. it will begin it's mas
sage over star of 95 magnitude.
| The occulation here lasts about 2Ia
hours. About IL p. m, April 20, it
will pass over another star of about
the eighth magnitude. This star is
very near the edge OF Jupiter and
will be hidden for but brief in
terval. Such occulations by planets
| are not very frequent 1t will re-
quire telescopes of considerable pow
| err. however, to see the faint stars
| in the glare OF Jupiter. Such obser-
| vations make it possible to investi-
gate the atmosphere and diameter
of Jupiter.