The Tipton advertiser. [volume] (Tipton, Cedar Co., Iowa) 1856-1962, 1874-10-01
How Eclipses Occur.

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i have SAID -eAa+- tlAe- -+ssH -+ssH ,s.a,---s..4s- ,,s.a,---s..
certain definite path among the star.
about half degree wide, which vot
could see ii he left any trace there
SO, also, if YOU could mark the pos,
tlon of the moon tonight among the
stars, and mark its position at every
hour during her whole course, you
would find that she also has purs ue,l
definite path among the stars. bat
YOU would not find this path t. be
the same as the suns path II il
were the same, we should have an
eclipse of the sun every time The
moon crossed the sun, ard an eclipse
OF the moon every time that the moon
passed on the other side of the earth
from the sun. Blu, the two paths are
inclined to each other about 80
They cross each other at II point
| which, in the month of October. 1874.
is very near the sun The moons
path is south of the suns in nearly
/
can see IN the evenings of that
mouth; but it approaches the suns
path, and crosses It near the eastern
horizon, and in most OF the invisible
half Of the sphere, or that part he
low the horizon, the moons path is
farther north. All this will be Gear
on examining the star maps. where
the dotted line shows the path Of the
moon during 1874, crossing the sun )
pa, h in the consultations Aries and
Libra.
These two opposite points in
which the moons path crosses the
path Of the sun are called the nodes
1t is very clear that unless the sun is
near one of the moons nodes when
the moon herself passes by, the moon
will pass above or below the sun,
according as her path is above or
below that of the sun at this point,
and consequently there will be no
eclipse. But if the sun happens TO
be near the node, then the moon will
necessarily pass over his face and
eclipse some portion of him. Now,
as ! have ust explained. there are
two opposite nodes; the one set a
few hours ago, and the other has Just
risen. Since the sun makes the
whole circuit Of the heavens in the
course Of a year, he crosses the
moons nodes twice in that time. In
! 1874 he crossed one node in Nav.
and will cross the other node in No
vember; consequently il is only
about these two times that any
eclipse can take place during this
year.
Ii the mo N always followed the
same path in the heavens, we could
never have any cclipses but a, those
two seasons But if we watch the
motions of the moon for several wears
in succession. we shall find that her
pate is continually changing. Al
the present time she passes seven
degrees north of Aldebaran: a month
hence she will seem to pass the star
at almost exactly the same distance: !:
bu, if YOU continue Your observations
for four or five months, you will find
thrt she passes it perceptibly farther
north, and in three years you will
| find thai she crosses il at the dis
tance Of abou, ten degrees. After
that she would begin to cross farther
south, passipg nearer Aldebaran at
every revolution for eight years, un-
til in 1885 and 1886 she will pass
right over It. If the moons path
were painted on the heavens, you
would see that every time the moon
came round to the same point in her
path, which takes place about every
tweniy-seven days. she would cross
the suns path about three of her own
diameters sooner than the month be-
fore. In the course OF year, there
fore, she will have crossed about
thirty-six diameters sooner, or farther
to the west. In the course Of twenty
years you will find that this motion
has been kept up until she crosses at
the same point she does now, and
thus the nodes have made complete
circuit of the heavens. The seasons
of eclipses vary, therefore, in the
same manner. This year they are in
May and October; in five years from
now they will occur three months
earlier, and we shall have them in
February and August; five years
more. and they will be in October
and May; five years more. in August
and February; five years more, and
they will correspond once more to
what they are now.-Uu7,er's My
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