Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1917-04-02
If You Could L1ve 10
Times 81 900 Years

els faster III lis OrDlt WneH IL is nearer
the sun and slower when it is far
ther, our winters are about week
shorter than our summers. So our
hemisphere is now in what may be
called the genial half of the great
equinoctial year. OF course, the op-
posite condition of affairs prevails in
the southern hemisphere, htt we will
deal with that later.
Now comes the effect of the revo-
luton of the poles, which will upset
our happy condition. The statement
that the earth's axis is fixed in po-
sition, while true enough when we are
dealing with ordinary periods of time,
is not true when we consider epochs
of thousands of years. 1t can be
likened to the peg of spinning top
which is inclined out of perpendicu-
lar. The end of such peg revolves
in circle, with a motion much slower
than the spin of the top. In a similar
way each end, or pole, of the earth's
axis revolves in circle, with one of
the poles of the ecliptic for its center
of motion.
The result Of this revolution, which
takes about 10000 years, is to pro-
duce, once in 10000 years, complete
reversal of the direction in which the
earth's axis points. Just now the
north pole of the axis leans in the d.
rection of the perihelion end of the
orbit, so that the northern hemisphere
has it winter when the earth is in peri
helion But in $4,000 years the north
pole will lean in the direction OF the
aphelion end of the orbit, and then we
shall have out winters when the earth
is in aphelion, and when it is travel,
ing siowest, so that the winters VIII
be colder and longer.
But, if you are going to understand
the whole of this wonderful business,
/ must next explain the swinging
round of the earth's orbit, which has
the effect of diminishing the length
of the great year." The revolution
of the poles is caused by what astron-
omers call the procession OF the equi-
noxes, and the motion is from east
to west, an entire revolution taking
10000 years. :.
The turning roundopf the orbit in
snace is called the motion OF the ap-
sides, the apsides being the perihelion
and aphelion points, and this takes
Mace from west to east. A complete
revolution Of the apsides-f the mo-
ton were constant, which 1t IS not
ouite--would require about lls,OO0
wears. Combining the effects OF me
procession OF the equinoxes and the
motion of the apsides, we find that,
since they swing round toward one
another, they bring about an entire
reversal Of the slope Of the earth.'s
axis with reference to the apsides IN
l0sOO wears, or $500 years sooner
than such a reversal would occur
through the action of the procession
alone In about 10000 years, then, we
shall have long, cold winters ana
short hot summers in our part Oh the
earth. a.,
A word about our neighbors south
of the equator. They at present have
the long cold winters and the short
hot summers that the future promises
! to us, but they suffer less from them
than we shall do because their hemi-
sphere is emphatically water hemi-
spbere. and a well-known effect OF an
oceanic climate is to mitigate the re-
suits OF extremes of temperature.
Al the same time'th southern hem
| ;snhere shows the effect of its long
and bitter winters in the vast accu-
mutation of ice in the Antarctic, Tar
Greater than that in the Arctic re-
s:ons Some astronomers and geolo-