The Bossier banner., 1891-11-19
EARTH VIEWED FRoMIrs MOON.
About Sixteen Times as Big as the Sun and
Blue.

About Sixteen Times as Big as the Sun and |
Blue.
1t is evident that to a 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 a
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 annular eclipse. Therefore, the
apparent sizes of these bodies must
average about equal in size to a terres-
trial 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 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
| 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 earth's atmosphere is blue, and
all things seen through it seem blue.
Even interstellar space seems blue
through this medium, and the unillumi-
mated parts of the moon can not be dis
tinguished from. the space that abuts it.
Bright, direct and reflected light is not
affected appreciably by its passage
through our atmosphere therefore,
stars, moonlight and distant illumina-
tions are not noticea5ly blue from that
cause.
1t may be well to examine sunlight
to see why it is not made blue in transit,
and as the moonlight is sunlight reflect
ed the explanation will do for both, and
in fact, for all. To the terrestrial OBJ
server of the sun there is visible an illu-
minated cone, the apex of which is in his
eye and the base on the solar disk. Re-
ducing this cone to dimensions that the
mind can grasp, we will adopt a scale
of 1000, 600 Of miles to the inch and inn
agine or construct a cone ten feet high
whose base is one-half an inch in diam
eter. Now, if the mathematical point
or aDeX of this cone be blue. five ten
millionths of one inch thick, which is
the proportion roughly, considering the
atmosphere to be forty miles high, it
will be seen why sunlight so easily
overcomes the color of air. If, how
ever, we construct cone to Illustrate
the view of the earth to lunar OBJ
server we must, to a height of ten feet,
have a base of two inches diameter,
with blue coat on that base one-siX-
tieth of an inch thick "a very thick card
is about that thicxness). Here the base
, of the cone is blue instead of the fine
point, and every ray travels through
!, the whole thickness of the atmosphere o1
, earth twice. The whole terrestrial disk
; covered by its blue envelope is seen at
once, and if, as we know to be true
the air colors distant objects blue to the
! observer on earth it must color eartf
r blue to a lunar eye.
| do not forget that when the eartl
a is full" to the moon there may be {
white spot or spots where the direc
, solar rays arc reflected to the moon, bu
that spot can not equal the apparen
a area of the solar disk, or rather one-six
teenth part of the apparent terrestria
o disk
y Of course, when the moon is eclipseC
to earth, the effect of the lunar observe
would be solar eclipse. Then the blu'
air should be visible around the edge o
earth slightly like that seen about tn
: moon in some cases of total eclipse AM
known as the corona. At such time
the aurora should family illuminate tn
@ dark side of earth and perhaps slightl.
be reflected on the eclipsed satellite.
o If we consider aurora borealis and it
a data, comparing it and them to nebul
7 and comets tails, we must believe tina
G earth has on the side opposite the sun
valuable streaming appendage of brigh
=" luminous effect Authorities, after di-
fering infinitely in results, now declar
;s that they are ignorant of the height
. which this phenomenon reaches. Hun
II boldt says ten degrees, which mean
,e any height according to the distanc'
The same aurora has been seen frol
70 the polar localities to fourteen degree
n north. No one knows their height, b.
cause our atmosphere may shut out
=, great part of distant effect, and moor
q light and twilight probably neutralil
the higher effects of all observers. II
-, only question is: Does the lunar o
~ server sec a tail streaming aft
= earth? And considering the clearne
4 that the tails of comets exhibit one hui
dred millions of miles distant and Wis
~ Bile nebula unknown millions of mile
in space, 1 assert that. aurora boreal
should be and is bright and beautif
trail after our great mothers glorio1
nt garment.
w There are many colored stars ar
u planets Mars is red. Venus is whit
IN Many stars are blue; in one group a
in are blue.-N. Y. Times.
or A Bright Idea.
eft The smart speeches of children are (
& wavs off-hand, consequently they al