The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1896-11-08

go
Rordame Comet as 1t Appeared July
Is, 1898.
generally be found that a line drawn
/ through the comet from the tail to the
head would, when continued around
the heavens, point to. the sun.
| In the present case il is plain, from
the position of the star tracks, that the
motion of the comet happens to be al
/ most perpendicular to the direction of
its tail. Considering the very flimsy
character of the tail of comet, it may
/ seem rather surprising that this struc-
! ture should not be swept backwards
so as TO stream out along the comets
track. Especially is this the case when
We think of the enormous velocity at
which the object is travelling. 1t must
however, be remembered that no atmos-
phere exists in the open space through
which the comet wings its fight. There
would be no other medium to offer any
resistance to the flight of the tail, and
therefore there is no difficulty in eX-
planning how the object moves sideways
through space as the photographs show
it actually does.
There is another very interesting cir
cumstance brought out by these photo
graphs of the stars, when we remem-
Der that they form a background with
respect to the comet. 1t will be observed
that many of the stellar streaks are
visible right through the tail. To ap-
preciate all that this implies we should
note that most of the stars here con-
cerned are in truth very faint objects.
They would, under any circumstances,
be quite invisible to the unaided eye.
Yet they are nevertheless distinctly
seen, notwithstanding slye inteTposi-
ton OF this stupendous volume of COM
etary matter. Here then, we see that
stars, even though they are faint stars,
can nevertheless be discerned through
a thickness of hundreds of thousands
of miles, of the material which forms
the substance of the tail to the comet.
This enormously thick curtain is quite
unavailing for the purpose of hiding
the stars. Yet the light from those
stars is so feeble that the slightest film
of haze on a summer sky would suffice
to extinguish them. This circumstance
shows, in a very striking manner, how
insignificant must be the quantity of
material which is contained in a comet.
We can admit this without, perhaps |
going quite so far as to agree with !
those who assert that he tail of a not |
able comet may, nevertheless, contain !
no greater quantity of solid material |
than could be packed into a portman
teau.
METHODS USED.
The remarkable movements of all |
comets, and the brilliant appearance
which many of these objects display.
make every circumstance with regard
to them of much interest. 1t wifi,
therefore, not be a matter of surprise
TO learn that the spectroscopic methods
Of research, which have already taught
US so much with regard to the sun and
the stars, have been applied to the eX-
animation of comets. The results are
very instructive, and we here give some
account of them.
We must first explain that there are
two totally different ways in which a
body may be rendered visible. In the
first case, it may shine by its own
light; in vthe second case, it may sim
ply show the light reflected from some
yther luminous body. The illumination
dispensed by a. sun or a star is if the
irst kind, that shed by the earth CT
my other planet is Of the second kind
ME first question which we have to
,sk with regard to the light received
rom a comet may be thus stated. Is
he light due to some cause of lun1in-
ss6ty in the Gomez itself, or is It merely I
-unlight reflected from the Gomez as
rom a planet?
If we had been restricted to the use
II telescopes, however powerful. ii !
you'd hardly have been possible for us :
o have solved this problem. The spec !
roScOpe has, however the power Of dcs- 7
ntangling the component rays in g ]
cam Of light, and thus indicating their
haracter in such a way as enables US p
0 learn what the source CT the light 4
FAY have been. We thus find thai ;
he light emitted from a comet is, gen !
rally speaking, of a two-fold cfu1ac- :
n. Part of it is undoubtedly reflected =
might. This is demonstrated by OBJ +
arvaticns with the spectroscope, which
how that part of the radiation from q
comet exhibits a continuous spec :
'um, marked by precisely these lines r
nd groups of lines which are distinctly ,
characteristic Of sunlight. The evil =
ence on this point is quite convincing :,
5e should, indeed. have been greatly X
Irprised had u been otherwise; fos =
hen the comet adventures SO near tbs =
IN, as it does in the course of rs !;
ander.ngs, it must be brilliantly :.
sh'ted up by the great luminary, and
course, some portion of the spie,n- >,
Sr thus produced is naturally reflected -
rs. -
OMETS AS LIGHT GENERATORS T
But besides the brightness which Y
'mets possess in virtue Of the sun III
INT Which they receive, IL is quite Ger w
in that they are also to be Regarded ell
being in a certain sense light gene w
tors themselves. In this respect chs b
met is at once perceived to be pc
Idy of tC-ally different character 81
ON Planet. The splendor of Venus pc
due simply to the sunlight which ii
rs upon it, Nor does the great Ju he
ter himself emit any rays beyond re
csc which he iTnperfectly reflect a
1m the sun. The comet is. however w
a. very different nature from tn, he
ore robust planets. Part of the Ugh tx
Itch the comet transmits is unaues of
nably due TO tncandescence in tn -
dy itself. If the sun were to be sud :
My deprived of light giving poTye. r
lille we were surveying the heaven, =
ntaining the moon and a planet an >.
bright comet, then the moon and tn H.
met would instantly disappear from n
Nv; but the comet might still Shin a
No doubt it would lose some of 1t -
ghtness, and probably the tail wouis on
to a great extent shorn of it's origi &c
proportions. There would. ho7 to
er, be a certain amount of cometar, J
hit independent Of the sun still forth ! !"