The Republican., 1890-02-22
The Camera and the Heavens.


A mariner, when drawing near
port at night, is guided by the two
entrance lights to the harbor. AS he
approaches he sees these two lights
separate, while when he leaves the
harbOr at night the farther he gets
away the closer do the lights appear
to draw together. Ina similar man
ner the astronomer observes the
| lights of the universe to learn whith-
pr the great solar system Is tending.
His beacOns are the stars, and in that
region towards which the sun is ap
preaching the stars seem to spread
away from each other, while in that
opposite region from which the sun
is retreating the stars seem to draw
IN more closely together. Indeed, il
is only by observing these changes in
the apparent places Of the stars, that
We learn the SUMS motion To in
vestigate the subject properly we
must employ large number of stars.
and we must wait a very long time
in order to measure their displace
ments with precision. This is exact
~ the kind of work in which the
photographs may be expected to
help us. Every plate will be care
fully treasured up, to be compared
with the plates taken in subsequent
years, and from the changes In the
apparent places of the stars we shall
learn with more accuracy than we
have hitherto been able to acquire
the true facts with regard to thai
mighty voyage through space on
which our sun and all systems is
journeyIng.
But there are many other aids
which photography renders to US in
Onr efforts to learn more of the skies.
One of the most difficult problems is
| that Of determining the distance of
stars. This depends upon very care.
FIJI measurements made between a
star and other stars in its neighbOr.
hood. 1t often takes an hour to
measure the apparent distance be-
tween two stars in the ordinary way,
bui in that hour the telescope might
he employed in taking a photograph
on which one hundred stars, or per
haps more. would be found, and the
distance between every pair of which
would admit of being determined
with accuracy.
Still, other and more marvellous
applications of photography to the
heavens have been made. The great.
est telescopes are often directed to the
observations of the nebuIa, or stains
and patches of light situated at in
! credible depths in space There are
| thousands of these objects known to
those astronomers who assidu0usly
cultivate this branch of their science,
and the nebul8 are all so faint that,
With single exception, they are in
visihleiU the unaided eye. The eX-
cpption is the Great Nebul9, in An
lrOmeda, which appears like a dull
spot of light, just vsable as glim-
ner on the darkest night. For ages
this object has attracted the attention
of astronomers, and numerous draw
ings have been made of it. But the
nature of the Great NebuI8 was new
er understood until IA few months ago,
when Mr.. Isaac Roberts obtained Il
marvellous Photographic picture of
the Iebul8, after an exposure of four
posed of a number of rings of gaseous
material. apparently IN a highly
heated state, and doubtless going
through some great process of trans.
formation.
Hardly less wonderful is the photo
graphic picture of the Pltiades. This
Well-kn0wn group of little stars ex.
hibits no nebuloSity in the telescope,
but after Il long exposure a nebuIae
is depicted on the plate. Here pho
tography has been the means of tel
ling Us of the existence mighty ne.
bulae surrounding the Pleiades, hut
which was quite unknown till the
photograph showed it. Even now
it has never been actually seen in the
telescope.