The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1869-07-17
The Light Of the Stars.

| the questions of the distances of the fixed
stars, and of the amount of light reaching
us from each star, are more intimately con-
early astronomical times it was not possible
to discover the distances of the stars by
parallax, so an attempt was ingeniously
made to discover how far they are off by
reasonings founded upon photometric mea-
surements of the comparative amounts of
light which they emit.
In total eclipse the moon takes a long
time to cover the sun, but if the sun were
removed from us to the distance of the
planet Neptune, the apparent diameter of
the sun would be so reduced that the moon
would eclipse it in ten minutes. Therefore,
as the suns, which we call fixed stars, are
eclipsed instantaneously by the moon it
follows that they are at enormous distances
from the earth. AS astronomers could not
at one time measure this distance by paral-
lax, they tried to find it out by comparing
the intensity of the light of the stars with
| the light of the sun. This however, was
visible the sun was below the horizon, and
when the sun was near the zenith the stars
could not be seen.
| This difficulty was surmounted by using
the planets as intermediate bodies, and Sa-
turn offering special facilities, was chosen
| for the purpose. The distance of Saturn
being known, as well as the extent to which
the suns light was enfeebled by reflection
from the planet, it was possible to compare
the intensity of the light from the planet
with the intensity of the light from the sun
and with the light from the stars. Mitch
ell, and other astronomers, tried this meth
cd, and found that the sun must be remov-
ed to 220, 900 times its actual distance to
| give us the same amount of light we receive
from bright star.
In these experiments it was necessary to
assume that the stars were of the same
| magnitude and splendor as our sun. Now
that the distance of some of the fixed stars
is known by the unoIjectionable method of
| parallax, it has been proved that the photo
metric measurements placed some of the
| stars nearer to us than their real distance.
1t follows, therefore, that those stars are
either larger in size or more brilliant than
our sun, and this is the way in which pho
tomctric measurements give some clue to
the relatise sizes of the stars, and show
| that some of them are larger and some
smaller than our sun. In the present state
1 g.. %a1 ,an1c i
impossible to learn the diameters of any of
the stars by actual measurement, their dis
| lance is so enormous.
The following is the result of the inca
surements of the intensity of the light of
some of the principal stars: Sirius, 4I6;
Campus, 204; Alpha Centauri, 100; Arctu-
rus, 70; Rigel, G6; Capella, 81; Alpha Lyre,
81; Procpon, 81; Alpha Orionis 40; Aide
baran, A; Antares, 80; Alpha Aqnil;e, 35;
Spica Virgins, 81 Fomalhaut, 26.
The excessive distances of the nearest of
the fixed stars are very difficult TO measure,
and with more distant stars the difficulties
of measurement are vastly increased. The
only clue to the distance of faint stars de-
ponds upon the space-penetrating power of
| telescopes 1t is assumed that the flintest
stars are those which are most distant, and
this is a very reasonable supposition, be-
cause if stars were pretty evenly distribu-
ted in space, the fainter stars should great
ly out-number the bright ones, and this is
the case in reality.
! Roses small reflector will bring into
view stars 100 times less bright than the
smallest visible to the naked eye. His for
| ty-feet reflector penetrates into space 1872
times further than the distance of the
smallest star visible to the eye, so that the
| furtherest stars revealed by his telescope,
are so far away that the light from them
takes about S,064 years to reach the earth,
| travelling at the rate of nearly 1000
miles per second. Yet through this tele-
scope, beyond these distant stars many 4
| faint haze is revealed, which might be re-
solved into other galaxies of stars, could
more powerful instruments be brought to
| bear.
In previous lecture Professor Grant
called attention to the peculiar light which
benefits the inhabitants of the worlds which
revolve round colored double stars. For
| instance the inhabitants of world which
travels round green and a red sun, must
have red or green day, according to which
sun chances to be above the horizon. Two
| or three months ago, Mr.. James Bucking-
ham, F. r. AS, was kind enough to let me
have two evenings with his great refracting
telescope, which powerfully separated many
of the double stars and resolved some of
the colored star clusters into magnificent
individual gems, the whole of them flash
ing more brilliantly than the finest jewels.
Mr.. Buckingham, by curiously RECONSTRUCTED
steam machinery, and long years Of labor
in which he was assisted by Mr.. Wray. the
optician, has overcome the enormous diff
culties in grinding great telescope object
glasses. The object glass of the telescope
just mentioned is 21i inches i'll diameter,
and perfect up to the edge, with fine
"black polish over its whole surface. |
believe it to be the largest obiect-glass in
the world in practical daily use. Although
many opticians have tried to make larger
glasses, think that none approaching this
in size has proved successful.-Britfsh Jour-
nal IF photographic.
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