South Bend news-times. (South Bend, Ind.) 1913-1938, 1917-12-31

and YOU can there sometimes in
the winter time see the grandest
display of the Aurora borealis. and
it is beautiful To look at NJ. II.
New York.
The explanations of the aurora
borealis that YOU quote are so often
heard. and so far from the truth.
that it seems worth while to point
out an easy way to detect their
fallacy.
Suppose you were in north lati-
tude 45 degrees at midnight in mid
winter. The sun would then be
6S - degrees below your northern
horizon and % II degrees below
the horizon of the north pole itself
Consequently its rays could not be
reflected from any ice and snow
within % II degrees Of the pole.
for it would be night over all that
region.
Even in midsummer the sun at
midnight would be q y degrees
below your northern horizon. and a
ray reflected from the sun would
pass more thar 1000 miles direct
~ above your mead In order TO
cause a visible illumination over
head, the light would have TO be
again reflected down TO your eyes
from an atmosphere thousands OF
miles high. But we know as a
matter of actual observation that
the air at an elevation greater than
80 miles is too rare to reflect a
perceptible amount Of sunlight. To
catch a midsummer nights reflec-
ton from the pole and make il
visible, not overhead, but close
down on the horizon, at 45 degrees
north latitude, the atmosphere
would need TO have, at a height of
700 miles, a degree Of density
which we know it does not possess
above so miles at the most.
In addition TO these simple geo
metrical considerations, you have
only TO recall the appearances pre-
scented by the aurora, with which
You are so familiar. in order TO per
ceive that it bears no resemblance
10 reflected sunlight. It's wonder
full Pickering. darting and rolling
motions. its strangely beautiful and
sometimes rapidly changing flush
es of color, and its tendency 10
form great arches and corOnal
circles which share but little, if at
all. in the incessant activity Of
other portions Of the Hsht are
quite sufficient 10 prove that the
aurora is an independent phe-
nomenOn occurring in the atmos-
phere.
When you speak of electricity
you hit the real explanation. but
il is difficult 10 see why il should
be thought that the electric illum.n-
alton is reflected from the polar ice
II could only be thus reflected if
ii were already in the air. and if
il is in the air it needs no reflec-
ton TO make it visible The fact
that the aurora boreais centers
about the north magnetic pole of
the earth, while similar lights are
10 be seen playing about the south
magnetic pole. gives a plain clue to
the origin and nature of these grand
and wonderful phenomena.
They are primarily due TO the
fact that the earth is a great mag
net, in the form of a ball 5000
miles in diameter, whose core is
probably largely composed of iron.
and which is circling in open space
around the sun, a vast center of
electric energy. Streams of cleo
tricity or Of electrified particles
from the sun traverse surrounding
space, and when they sweep over
the rotating earth produce many
electro magnetic phenomena. among
which are the polar lights which
seem 10 signal back 70 the sun.
When the output Of energy from
the sun rises TO a maximum. as It
does at more OF less regular inter
walls. the earth feels the effect in
the shape Of magnetic storms and
displays Of electric light in the
atmosphere.
In the neighborhoo6 Of the.
earth's magnetic poles the lights
are almost continually visible and
often very brilliantly. but al great
distances from the poles. as in the
latitude OF New York or Washing
ton. for instance. these displays are
rare, being seldom Witnessed ex-
cept az times when great spots on
the sun indicate a state Of extreme
disturbance OF the solar energies.
such. in brief. is the Sc entihc ex-
PLANTATION Of the aurOral lights. If
you wish study details that have
been worked out by various in
vestigators read the books and pa
pers on this subject written by
Arrhenius. Birkeiand Norimann and
others