The midland journal., 1914-11-20
AE MIDNIGHT sun
" Seen but Once a Year in
the Polar Regions.
! SWING ROUND THE HORIZON.
For One Whole Day, About June 21 at
the North Pole and About Dec. % at
the South Pole, Old Sol Keeps Hia
Blazing Face In Full View.


the South Pole, Old Sol Keeps EIie
Blazing Face In Full View.
sThe midnight SUM- is one of those
seemingly mysterious natural phenom-
ena which exercise perpetual charm
over the popular imagination. The
northern part Of Scandinavia has ac-
quired for itself the distinctive name
OF the "Land Of the Midnight Sum-"
but the title should be extended to In
clude d complete circuit Of the earth
along the arctic circle. Then, too. the
southern hemisphere has precisely
similar phenomenon, which occurs
along the antarctic circle, including a
portion OF Wilkes Land
Properly speaking. midnight sun
Is seen but once year in either hemi-
sphere
Conining our attention to the north
ern hemisphere. the midnight sun is
visible near the arctic circle on the
date of the summer solstice, which oc-
ours about June 21 at the time when
the sun In its apparent annual circuit
1pf the sky reaches its greatest north
IN declination, which means its great
~ Y &distance north of the equator. This
pee in angular measure Is about
degrees. which is precisely equal
Grach inclination of the earth's axis
and alton from perpendicular TO the
opae Of It's orbit around the sun.
The arctic circle Is situated this same
angular distance (231a degrees, from
the north pole. When the sun is di-
rectly over the equator. about March
vi, It's light reaches simultaneously
both poles of the earth. AS the sun
begins to move northward the light
quits the south pole, which then en-
ters its period Of six months night
But at the same time the sun rises
higher at the north pole. which In its
turn enters upon its period Of six
months day.
In the meantime, along the arctic
circle, the days grow longer and the
nights shorter, as the sun comes con-
tinually northward, until, at the SOL
stice. when the sun is 231a degrees
north of the equator. there will be one
period Of twenty four hours during
which the sun does not set at all In
the arctic circle
At the hour of midnight on that day
the sun, describing a circle through
the sky, just touches the edge Of the
horizon In the north, like the bob Of a
gigantic pendulum, and then, without
disappearing, Immediately begins to
rise again to describe the other half
of Its sweep in the sky.
This is the phenomenon called the
midnight SUM-
Conversely at the time of the winter
solstice, which occurs about Dec. %.
when the sun is at its greatest south
ern declination, there is one absolutely
sunless day on the arctic circle, when
the sun skins just under the southern
horizon at noon.
As matter Of fact. owing to the
effects OF the refraction of the atmos
phere. which means the power of the
air to bend the rays of light so that
the sun appears to be above the hori-
20n by about its own diameter, when
1t is really its own diameter below 1t.
the phenomena just described are Wis
ible half degree (about thirty-flve
miles) south OF the arctic circle.
After the day of the solstice the sun
begins to dip below the horizon again.
because it is then going south once
more, and the nights, beginning with
af length OF only q few minutes. grad
uAliy increase until they, too, for one
single occasion, attain the length of
twenty-four hours.
Within the arctic circle the days and
Nights. alternately, greatly exceed
tWenty-four hours in length. At the
very pole, as we have seen. they each
last six mQnths. In Lapland they may
be month long and at the North
cape three months.--G Garrett p. Serviss
In Spokane Spokesman Review.