The record-union., 1891-08-18
EARTH VIEWED FROM IT'S MOON.
Sixteen Times as Big as the Sun an
R1na-


Sixteen Times as Big as the sun and
Blue.
1t is evident that to lunar observer
the disk of earth appears to be equal to
about sixteen areas of the solar disk. The
solar disk, as seen from earth. is on an
average equal to the lunar disk seen from
the same point, for, in solar eclipse, the
disk of the moon covers the sun in total
event OF that character, while it fails TO
cover the sun in an annuaiar eclipse.
Therefore, the apparent sizes of these
bodies must average about equal in size
to terrestrial observer. Again, the solar
disk will appear to the lunar observer
just equal to what it seems to be when
seen from earth, because the distance
from the sun to the moon averages equal
to the distance from the sun to earth.
Furthermore, the diameter of the earth is
equal to about four lunar diameters, and
of course the areas of their disks vary as
the square of their radii, and this makes
the terrestrial disk about equal to sixteen
lunar disks, and, Of course, If the lunar
disk is equal to the solar disk at given
distance, then the terrestrial disk will
seem to be about sixteen times as great
at the same distance.
This enormous disk of earth must be
blue in color to the lunar observer, be-
cause earths atmosphere is blue, and all
things seen through it seem blue. Even
interStellar space seems blue through this
medium, and the unilluminated parts OF
the moon can not be distinguished from
the space that aDutS it. Bright, direct
and reflected light is not affected appreci-
bly, by its passage through our atmos-
phere; therefore, stars, moonlight anu
distant illGminationS are not noticeably
blue from that cause.
1t may be well to examine sunlight 10
see why il is not made blue in transit,
| 4 y
the explanation viii do for both, and, IN
fact, for all. 70 a terrestrial observes Of
the sun there is visible All illuminated
cone, the apex OF which is III his eye and
the base on the solar disk. Reducing
this cone to dimensions that the mind
can grasp, we Will adopt n scale Of 9,000,
600 miles TO the iEch, and imagine or con-
strnct cone ten feet high whose base is
one-half ali inch III diameter. Now, if
the mathematical point or apex Of this
cone be blue, five tenmilliontEs Of one
| inch thick, which is tie proportion
roughly, considering the atmosphere to
! be forty miles high, it viii be seen why
sunlight so easily Overcomcs the color OF
! air. II. however, we construct q cone to
! illustrate the view Of earth 90 a lunar Cb-
server, we must, to a hight Of ten feet,
! have a base Of two inches diameter, with
! Il blue coat on that base OnC-SiXueth of an
inch thick "a very thick card is about
| that thckneSs). Here the base OF the
cone is blue instead Of the line point, and
every ray travels through the whole
/ thickness of the atmosphere OF earth
twice. The whole terrestrial disk covered
/ by its blue envelope is seen at once, and
! if as we know to be true, the All cOiOrS
distant objects blue to the observer on
earth it must color earth blue to q lunar
| eye.
do not forget that when earth is "fuli''
Of
| spots where the direct solar rays are re-
| tlected to the moon, but that spot cannot
equal the apparent area Of the solar disk,
/ or rather onG-SiXteepth part of the Qp-
parent terrestrial disk.
OF course, when the moon is eclipsed
to earth the effect to the lunar observer
would be solar eclipse. Then the blue air
should be visible around the edge Of earth
slightly like that seen about the moon III
some cases OF total eclipse and known rs
! the corona. 1T such times the aurora
should family illuminate the dark side Oi
the earth and perhaps slightly be reelected
OH the eclipsed satellite.
If we consider aurora borealis and its
data, comparing 1t and them to nebula
and comets tails, we must believe that
earth has OH the side opposite the sun a
ycritabla streaming appendage OF bright
luminous effect. Authorities, after diff
fering infinitely in results, now declare
that they are ignorant OF the night tC
which this phenomena reaches. Hum
bOldt says ten degrees, which means any
hight according to the distance. The
same aurora has been seen from the polal
localities to 10 north. No one knows
their hight, because our atmosphere may
shut out a great part of distant effects
and moonlight and twilight probably
neutralize the higher effects to all ObserV-
erS. The only question is, does the lunar
observer see a tail streaming after earth?
And considering the clearness that the
tails of comets exhibit l00,000,000 miles
distant and visible nebula unknown
millions Of miles in space, I assert that
aurora borealis should be and is bright
and beautiful trail after our great mother
glorious garment.
There are many colored stars anG
planets. Mars is red, Venus is white
Many stars are blue; in one group all are
blue.-N. y. Times.