, 1879-04-04
COME'l'ARY,
Drorscn's Comot Nav Visible with a Tclc.
scope.

6COnGs
Ns,c lorE 7ymss, lnrch n.
Bsorscn's comet IL now visible tp tho western
sky with good telescope Of three or four iucl,es
aperture. It comes 10 Its pcrihelion on the gOth
inst, md will reach It's greatest brightness
about the middle Of April, though even then It.
will probably not be bright enough to to DO seen
by the naked eye, It Is now moving slowly
toward tile northeast through the constellation
OF Aries, rather too near the horizon at present
Tor satisfactory observation, but everyday ine-
proves Its position. III tho telescope it shows
as small round mass of hazy light mitch
brighter At the centre, though without auy def
nito nucleus, and fading out ut the edgos
80 gradually that H. is impossible TO de-
terminc IT'S diameter with much accuracy.
IT, would be fair estimate to nut Il
aud minute Of asc, which, at Ito present dis
tancc, would correspond tn u diameter VI from
twent5-f'vg to thirty thousand mites,-bcswce,,
thrcc mud four times TINT Of tho cnrth II las
= million OF miles, tn leu%sh, consisting OF q
single straight pencil Of light, considerably nas-
rover than the diameter Of tho comck's head,
aud streaming backward LII a direction OBJ
ance with telescope OF about ten inches
nprrtArc. II Is possible that larger instru-
Inent might slow the tall wider as wcll as
longer. Thts kiud OF ta']. though Dot i,u-
npnroaclfng the stu. ORDINARILY, the tatl, even
whcto the narrowcat, Is wider than tho whole
diameter OF tic comets head, aud ia brighter at
tbc edges than IN the CENTRE. accmtng to DO
formed Of matter swept of from Tint por-
ton Of the comets surface most directly
exposed to tho aolar rays, carried arround tic
edge, anu driven to the rcnr by some rcpcltnnt
toscc o. natnte not W. perfectly aseertnned
ever, sccms to be cryatall!zing muro und moro
Into tho belief that the ropulsion ts Il true elcc.
trls phen,pmenop. denend!pe upon the sudden
auot,asr--the sun-simi'nrly electrified.
:, we have not yet Econ any statements as to
the spectrum Of this comet, we prcs,l1nc gmp]y
because It has bccn too faint md badly Situated.
NO. il was examined 81 sir. MuxcI,,s, % md as1'e liz
Apectrun was found to DO peculiar, md diiYerent
from tslat Of any ot,er COMET observed before or
since. tho difference lying In the position and
characterize it. All comets Except this, 80 fur
as hitherto obscrycd, show n spectrum which
seems to correspond prucisely with thnt obtu,u-
e. ff from tneande.cent carbon gases; but Nj:
into ltno at AlE It Is, perhaps possible tllat In
tlc ttcn existing state Of spcctroaruplc obscrya-
tnat sohc error may have crGpG In: ut my rate,
te result needs either confirmation or corrcc-
ton. a prinrl, 1t would have seemed !saprob-
aole tllus different comets ahoul1 nll show thu
game spectrum. for tllnY seem to cumc to US
from widely different parts Of space, and there
Is no evident reason for their resembling each
other at all. Since, however, so mauy have been
found really to resemble cact other In spcctro-
scopie characters, It becomes an lntorcstin. and
Important problem to asccrtain whether or not
there Are exceptions, md II there are, 10 juvest|-
gate The pccslfarltfcs OF origin unA constitution
TO which they arc due.
This comet belongs to the cluss Of periodic
comets, so-eallcd, with ttmc OF revolution Of
very ncarly five ind (ulf years. II was llrss dis
covered ~ Hrorscn. Of klcl, whosc name It
bears, IN 1916; n.nl sincc then has made ak cum
plcte circuits, having been four times observed:
~ 1851 a,iu lt3 It was nntnyornbiy situated III
tho hky ard was not Eccu. At its nearest ap-
lrt,ach to tic sun-iss perlhston, us 1t is called
within the orbit Of Venus. The other extremity
OF its long clitpsa lies outside tho orbit OF
Jupiter ut diatanco Of b90, ,DO0, QUO miles. On
thu pTeaent OCCASION tic cOpyet, when nearest tu
ltie osrtli. which will be In May, will bo about
M,No.ooo miles from It's, though, on account
ot hs Increased Itstu.ce from the sun,
dlo OF April, when somo 1o,o0o.0o0 more re-
mute. Ono would naturally suppose tii,,t this
comet ought to lavo been Boen 'befure 1916, X
u were then moving tn its present orbit. Prob.
AfAy 1t gonta have boon. On examining tic
matter. BY tracing back ita tnutiot Of 1919, 1t
appcars that II WIS then very hear the great
t'!anot Jup!ter, a'hs the computation Of U'Ar-
rust, who Investigated thu subject III 1865, {puj.
ratu tlsat previously It l,ad beun moving In AZ
clipse, whOsa pGrtholjon waH Mt distaucu OF
nbont l40, ,000, coo of miles from tho suu, upd
Gute beyond lhe reach Of terrestrial Observers
4 second faint comet also Is now duo Ia tho
constellation of OphucEus--Temple's comet Of
1877, which Inns prrIod ol utmost exactly six
sears. II was obaerYetl ia 1873, utAt ought now
to be In sight agA!n, Or ut least to make tts w.
pearanco very soon. Its pcrihelInn passbEa ot-
c,lrs MaS to.