Omaha daily bee., 1916-11-30
Heavens IN December s Ssf 1 81 z 3 S %s M T
Of One the Unusual Mae Terrestrial Geography and Sal Astronomy
By WILLIAM F. RIGGE.

an eclipse of the Christmas midnight
sun. Although nothing whatever OF
Il will be visible to us In Omaha, the
occurrence itself is so interesting that
1t may we'll find place here. This
eclipse, which is In a certain way the
most remarkable that can possibly
occur, will come when We are busily
preparing for Christmas, that Is when
our clocks show p. m. central time
on Christmas eve. We in the United
States will not even get a glimpse OF
1t nor will any one in the whole OF
North and South America, nor in the
wide extent of the Pacific ocean. For
us and for all these lands and seas the
sun will be shining undimmed in Its
full splendor, as far as the weather
and the season permit, But far away
in the Antarctic ocean, about half
way between the Cape of, Good Hope
and the South Pole. over limited
tract of unfrequented waters, the sun
will be eclipsed to such tiny extent,
trifie over per cent, that 1t seems
to be a downright waste Of time, If
not absolute folly. to mention 1t at
all. But for the ships that may be
there to see it, the eclipse will occur
when some Of them have midnight,
Christmas midnight, while others have
any hour or minute on Christmas eve
from 9:41 D. m. to midnight and few
have already for a few minutes after
midnight begun Christmas day.
Look at figure 2 for explanation.
Here we have the earth, the sunlit
hemisphere, as it will appear to the
sun at 2:40 p. M. central time. The
sun will then be overhead in the CEN
ter of the figure. in latitude % degrees,
25 minutes south, and in longitude $50
degrees west. The greater part OF
North America, and all except the ex-
IRENE eastern part Of South America.
the whole Pacific ocean and a part of
Australia will then have day. AS the
earth is turning eastward on its axis,
that Is, towards the right in the dia-
gram, the sun will be setting all along
the entire right half of the circle that
is seen to bound the terrestrial globe
in figure 2, and rising all along its
left half. The north pole Is not visi-
BILE, it is In the middle of its six
months darkness. The south pole,
however is in full view, and as the
date is but few days after the win
ter solstice, the suns rays shine %
degrees and rs minutes beyond the
South Pole, so that II the earth did
not move in an orbit around the sun,
but only turned on Its axis, all the
sunlit region about the South Pole
would have perpetual day.
The line N s crossing the earth is
the central meridian, the only one of
all the meridians on the earth to be
projected into a straight line at the
time mentioned, when our clocks show
2:40 p. M, central time, on Christmas
eve. Its longitude, as said before, is
act IL al n
1t is noon. II we were to start at the
very top of the figure near the letter
N in latitude 66 degrees, IS minutes
north, the sun would be seen to just
rise above the southern horizon at
midday For every degree of latitude
that we go south on this central merid-
ian, the sun Is one degree higher at
noon, and the day is getting longer.
From few minutes in latitude 66 de-
grees IS minutes north. 1t lengthens
to twelve hours at the equator, where
it's length never changes all the year
round When we come to latitude
20 degrees, rs minutes south, to the
place in the exact center of the dia-
gram, the sun is directly overhead.
As we proceed southwark, the sun be-
gins to sink towards the north. The
day is all the time frightening and
becomes equal to twenty-four hours
as we reach latitude &C degrees, IS
minutes south, beyond which it
lengthens rapidly until it becomes six
months long at the pole.
As soon as We arrive at the south
pole, there is no direction but north,
since we cannot possibly go farther
south than the south pole, and when
we have reached it, any further mo-
ton must take US away from it, that
is, carry us north. Hence, as soon as
we have passed the South Pole, while
we continue on our straight line or on
our great circle, we are going north.
the sun is now south of us, instead
of north, as 1t was before, and noon
has changed to midnight. The sun
is visible until we come to 66 degrees.
IS minutes. south latitude, the lower
most point on our diagram, when 1t
will sink below the south horizon. All
the way between this latitude and the
pole, we can see the sun at midnight.
AS we leave this limit, that is, pro-
coed on our northward journey past
the lowermost point on the diagram
and enter the dark hemisphere, the
sun begins to dip more and more be-
low the south horizon at midnight.
And all that has been said about our
journey from 66 degrees, 35 minutes,
north latitude, across the sunlight
minutes, south latitude, beyond the
south pole. will be repeated in the
same order II we exchange night and
day, and north and south,
l must call attention to another
fact, that u.s. as soon as we passed the
south pole, our meridian changed 1870
degrees, from being 1870 degrees west,
1t becomes 50 degrees east. We will
need all these facts to understand the
exceptional circumstances Of the pres
ent eclipse.
The reader will also notice that
only two meridians have been drawn
across the south pole for the region
within ten degrees of 1t. This was
done to avoid confusion, since all the
meridians meet at the poles. The
two, or we may say, the four that
are drawn, are first, the meridian of
Greenwich. which is the one to the
right and below, and quickly enters
the dark hemisphere, The second
one, the upper one to the right, is
the ninetieth meridian, which we may
trace through the middle of the Gulf
of Mexico and the United States, and
which Is our own standard meridian
six hours slow Of Greenwich. The
next one on the diagram is the 1S0th
meridian, on which all mariners
change their date, dropping a day
when going west and repeating it when
going east. The last meridian drawn
across the south pole, the lower one
to the left, is the ninetieth east of
Greenwich.
We may now turn our attention TO
the two circles below the terrestrial
sphere on figure /. The smaller one
is the moon Its center moves along
the line ABB. where its position is