The Nashville globe. [volume] (Nashville, Tenn.) 1906-193?, 1910-04-22

more than one comet scare. One or
these startled Europe in 1882. On
October 29 of that year Biela's comet
crossed the earth's orbit. The an
nouncement was received with stupe-
faction. 1t was only when Arago
soothingly pointed out that the eartn
would not reach the exact point where
the comet had intersected the earth's
orbit until November 80, at which
time the comet would be 5O,OOO,0OO
miles away, that the popular excite
ment subsidized. A similar alarm
seized the world in 1857 Some proph-
ct declared that on June 13 the world
would collide with certain periodic
comet having a period of revolution
of three centuries. 1t is related
that the churches and confessionals
were crowded for days. Still another
prediction, made in 1872 by Plantar
mour. the distinguished director OF
the Geneva Observatory, set Europe
in a ferment. His calculations were
based on errors, which were pointed
out by others, and the public mind
was Quoted.
Although more than two centuries
have passed since HALEY was In MS
prime, the possibility of a collision
with some vagabond star still fascl-
mates the astronomer. According to
Babinet, a chance encounter is likely
to occur once in about 100000
wears. Arago stated that out of 281,
100000 chances there was just one
that the earth would collide with
comet. A blind man bent upon duck
shooting is apparently more likely TO
hit his mark than the earth to ram
comet. There is, however, this
difference between the blind man and
earth. A sightless marksman has
only a limited space and limited
lifetime in which to indulge in duck
shooting; the earth and comets, on
the other hand, are wheeling around
the sun in infinite time and Infinite
space. Automatically, one chance
in 2S1. 100000 is far better than the
gamblers chance of breaking the bank
at Monte Carlo. An con is no longer
than a century in the career OF a
world, a year but a fleeting second.
Araeo's fifteen million years are astro-
nomically only a few ticks OF the
great clock of eternity. That q col
lision is bound to occur is, therefore,
no inconceivably remote possibility.
The latest estimate, made in 1909
by Professor William H. Piskering,
of Harvard University, would seem to
prove that the core of one comet in
about 1OO,O00,OO0 will hit the earth
suuarely. Such a square collision, in
his opinion, is likely to occur once in
about 4OO,000000 years. An en-
counter with some part of a comets
head will happen once in 4,OOO,OOC
wears. Since comets orbits are more
thickly distributed near the ecliptit
than elsewhere in the celestial sphere
the collisions will occur, according tC
Pickering, rather more frequently
than this, but hardly as often as
once in 100000 years. Because
Pickerings figures differ from those
of Arago and Babinet it must not b'
inferred that his predecessors arr
wrong and that he is right in hi
calculations. The problem is TOT
simple for that. Pickering, Arag'
: and Babinet differ partly because the!
have assumed different average size
! for their comets and partly becaus'
4 their definition of visible comets ar
not in accord
4 That the possibility is very rea
: we shall all have an opportunity o
Y Judging on May Is, 1910 On tina
n date the earth will be plunged in tn
e tail of Hallcy's comet, and the hea
d will be less than than 100000 mile
away--a mere hands breath in tn
/, vastness of the universe. What wi
S happen? Nothing beyond possibl
5, auroral glare and a shower of me
e eors. Twice in the last century ma
4 the earth been thus whisked by
n comets tail-in 1919 and 1861. o
t. neither occasion was any one tn
,e wiser until long after when tn
ct mathematician announced the fac
n From this it may we'll be inferre
o. that the texture of a comets tall
d, diaphanously thin. In truth, a
n though comets tail may exceed
es hundred million miles in length, II
pc amount of matter which it contains
be amazingly small. The actual stu
Of composing the tail Of Halley's com
Id could probably be packed in an orc
a nary room, so wonderfully rare is tn
b. ghostly sheaf The thinnest haze
Id the horizon is a stone wall in col
ar parison with the fairy veil of HALEY
comet,