El Paso herald. (El Paso, Tex.) 1901-1931, 1917-09-29
PIelades Seen Without the
Means Of Telescope; the
Disappearing Comet.


y found on the October sky map
4 >5he cluster of the Pleiades and
the remarkable variable Mira in the
constellation Of the Sea Monster, Ce-
tus The Pleisdes In. the group
Taurus are what is called d naked
eye cluster. because without the aid
Of the telescope we can make out
some Of the. component stars OF the
cluster. We must never make the
mistake Of confusing a cluster with a
Iebula- though without sufficiently
powerful msgnificauon the error IS
easily made. But the two are very
different tificauy-
a nebuaa is Of gaseous compost
ton, with perhaps one or more con-
densa1on nuclei, but, on the whole
the matter in a nebula Is a true gas
nearly always in lumlnesceut condi-
zion; we know that from the spectre
scope On the other hand, the cluster
Is only an assemblage Of distinct and
separate stars, each one Itself q sun
There may or may not be systemic re-
latfon between the different members
-o1-What appears asa cluster 10 US; il
may be that only by projection do
they appear close to one another and
so grouped together, while in truth
they are AT great astronomic dis
tances from each other and quite un-
related
The PIeiades Visible.
The Fleiades contain SIX stars
which are easily visible to people Of
ordinary vision. and a seventh which
those with particularly keen vision
can see under good atmospheric con-
ditious- More than a hundred can be
seen with 6. small telescope. It Is in
terestinE to note that several Of the
larger Fleiades are surrounded By
nebulous cloud
The slar Mira OF Omicron Ceti was
lions OF brilliancy We're recognized
It was 1oticed by Fabricius IN 1886
ana since then its variations in brill
Iancy have been carefully studied
and recorded II IS curlously lrreeu-
lar in its actions, differing greatly
from q star like Algol in Perseus,
whose variations are regular, both as
10 tine and degree. Mira attains al
most second magnitude at some % us
times Of maximum ordnance and 1alls
20 ninth at a minimum It Is then Of
course. invisible 20 the naked eye
Once it reached the brightness Of
Aldebaran and somewhat later
dropped down so as 10 be 1nVlsl bic
even in good sized telescope when
visible 10 the naked eye it has dis
tinct reddish color.
The Disappointing Comet.
Comet B1916 lWolfb has certainly
been q great ap7Ointment TO all
astronomers. amateur and profession
al When first discovered IL was eX-
tremelT Ear away and this meant mat
Il was then unusually brilliant I'm
medistely a great new. naked-eye
comet was promised, d hairy star,
to rival Haley's comet which We
saw in 1910. But, curiOusly enough.
the comet never reached a brightness
which made IL visible 10 the unalded
eye. something happened to II before
II had passed very FAR into the solar
system We cannot tell definitely
what this something might have been
hw~ are surely nernirre0 to ma Ike
a guess in that direction We have
before rs the usually accepted eX-
PLANTATION of The formation and main
tenance- of the cOmetary tails based
upon Maxweu's phenomenon OF light
pressure Light falling upon material
bodies eEerts a small but definite re-
pulsive pressure. The ordinary forces
material and gravitatonal. which act
upon BODY Of greater than micro
scopic size. are so great by compar1-
son as TO make the force OF the light
absolutely imperceptible.
The Pressure OF Light.
II. however, we imagine a body
growing smaller and smaller the sur
face area becomes greater in con-
parison with the mass or substance
contained The light pressure is pro-
porionsl to the surface upon which
ii falls and gravitationai attraction
is proportional to the body's mass or
weight Now, in the head Of the
comet there are particles Of all differ
proaCh the molecular size On these
latter the repellant force OF the suns
radiation viii be greater than the at
tracing force OF the suns gravita-
ton. and they viii be pushed out o.
the head Of the comet TO form its tail
and finally may be entirely discon-
nected from the comet, which prob
ably has only weak attracting force
So that every comet when il passes
near TO the sun loses a part Of its
substance. may we not then be al
lowed 70 guess that our friend,
B1916. as It approaches the sun. lost
and alarming extent as 70 be really
very materially changed In bright
The Planets for October.
Mercury is a morning star during
October II reaches its greatest dis
lance from the sun on October 4, and
viii be Iuteres tingly in view in the
eastern morning sky about an hour
before sunrise during the first half OF
Venus is steadily Increasing in
brightness in the western evening
sky. Tt comes into view Immediately
after sunset and sets about two hours
later It is in Libra on the list and
Antares in Scorpio on the 18th. and is
in close proximity 10 the moon on the
same date, being occulted BY the
moon In some tropical regions on this F..
date.
Mars and Saturn viii be most inter h.
aEtinEIy II eaniun ctinns IN tia eastern