The times., 1900-12-30
THECREATION OF WORLDS
Nebula May Be the Stuff of Which
Stars Are Made.
Their Form. structure. and Di-tribu-
tion-Recent Discovery That They
Are Mostly SpiraIs-Somc Questions
About the Univcrse-Astronom
Predictions for January, 1901.

Scattered about here and there among
the stars are certain patches Of faint
luminosity called by astronomers nebu-
lac. These little clouds OF nimy
light are among the most fascina ing of
all the Kaleidoscope phenomena of the
heavens; for it needs Dut a glance at one
of them to give the impression ha tlere
before us is the stuff of which worlds
are made. All our knowledge of nature
leads us to expect in her finished work
the result of a series CT gradual pro- cesses
of development. Highly organized phe-
nomena such as those existing in our
solar system did not spring into perfec-
ton in an instant. Influential forces.
easy to imagine, but difficult to define,
must have directed the slow. sure trans
formation of elemental matter into sun
and planets, things and men. Therefore
a study of these forces and of their prob
able action upon nebular material has al
ways exerted a strong attraction upon
the acutest thinkers among men of exact
science.
Our knowledge Of the nebulae is of two
kinds-that which has been ascertained
from observation as TO their appearance.
size, distribution. and distance. and that
which is based upon hypotheses and theo-
retieal reasoning about the condensation
of stellar systems out of nebuiar masses
1t SO happens that our obseryational ma
terial has received a very important ad-
dition quite recently through the appli-
cation of photography to the delineation
fhl
further on
Two nebulae only are visible to the un-
aided eye. The brighter Of these is in
the constellation Andromeda; 1t is OF oval
or eiliptieal shape, and has distinct cen
trail condensation or nucleus. Upon pho
tograph by Roberts it appears to have
several concentric rings surrounding the
nebuia proper, and gives the general i'm
preston of fat round disk foreshortened
into an oval shape on account of the OBJ
servers position not being square to the
surface of the disk. Very recent photo
graphs of this nebula. made with the
three-foot rejecting telescope of the Lick
Observatory, bring out the fact that il
is really spiral in form, and that the
outlying nebulous rings are only parts
OF the spires in a great cosmic whori
This And-omeda nebula is the one in
which the temporary star of 1885 ap
peared- 1t blazed up quite suddenly near
the apparent centre of the nebula and
continued in view for six months, fading
finally beyond the reach of our most
powerful telescopes. There can be little
doubt that the star was actually in the
nebula, and not merely seen through it,
though in reality situated in the extreme
outlying part of space at distance i'm
measuTably greater than that separating
US from the nebula itself. Such an acci-
dental superposition of nebula and star
might even be due to sudden incandes-
cence in new star between us and the
nebula. In such case we should see
the star projected upon the surface of
the nebula. SO that the superposition
would be identical with that actually OBJ
served. Therefore, while it is indeed
possible that the star may have been
either far behind the Lebula or In front
OIL II, We must accept as more probable
the supposition that there was a real
connection between the two. In that case
there is little doubt that We have actually
observed one of those cataclysms that
mark the successive steps of cosmic evo-
luton We have no thoroughly satisfac-
tory theory to account for such an ex-
plosiye catastrophe within the body of
the nebula itself
The other naked-eye nebula is in the !
constellation Orion. In the telescope it is |
a more striking object, perhaps, than the
Andromeda nebula; for it has no weii-de- |
lined geometrical form, but consists of an |
immense odi-shaped mass of light enclos- I
ing and surrounding a number of stars. II !
is unquestionably OF very complicated /
structure, and is therefore less easily |
stuoied and explained than the nebulae of |
simpler form. There is no doubt that the
Orion nebula is made up of luminous gas.
and Is not merely a cluster of small stars
too numerous and tco near together to be
separated from each other. even In our |
most powerful telescopes II was. indeed |
until about forty years ago. that |
all the nebulae were simply irresoIyable /
but We now have indisputa-
bic evidence, derived from the spectro-
scope, that many nebulae are composed of /
true gases. similar to those with which We
experime mt in chemical laboratories. This /
spectroscopic proof of the gaseous char
ecter of nebulae is one OF the most inn
portant discoveries contributed by that in
to our small stock of facts con-
cernlng the structure of the sidereal uni
verse
coming now to the smaller nebulae. we
ind great diversity of form and appear
ance. Some are ring shaped, perhaps hav-
ing less brilliant nebulosity within the
ring Many show central condensation
OF disk-like appearance (planetary nebu-
lael. or have simply star at the centre
tneoulous stars. Altogether about ten
such objects have been cata-
logued by successive generations of as
tronomers since the invention of the teIe-
scope, and most of these have been re- /
ported as oval in form. Now we have al
ready referred TO the important addition
TO our knowledge of the nebulae obtained
by recent Photographic observations; ard
his addition consists in the discovery II at
most of these oval nebulae are in reality
'pirals. Indeed, It appears that the spiral
type is the normal type, and that nebulae
'f irregular or other forms are exceptions
% the general rule. Even the great An
iromeoa nebula, as we have seen, is now
recognized as spiral The instrument
with which its convoiute structure was
discovered is a three-foot rejecting tele-
scope. made by Common of England. and
low mounted at the Lick Observatory In
California
The late Prof. Keeler devoted much of
MS time to photographing nebuIae dur
ng the last year or two. He was able to
establish the important fact Just men
Toned, that most nebulae formerly
.hougnt to be mere ovals. turn out to be
spiral when brought under the more
searching scrutiny of the Photographic
)late applied at the focus of a telescope
u great size, and with an exposure to the
eebie nebular light extending through
hree or four consecutive hours Many
" the spirais have more than single |
ioiute- 1t is as though one were to at
aeh number of very flexible rods to
IN axle, like spokes of a wheel without
! RIM. and then reyolve the axle rapidly |
The flexible rods would bend under the |
pid rotation. and form a series of sniraI |