Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-11-28
METEOIITES FROM THE MOON.
Prof. Coaklcy Argues That They Were
Shot Out by Lunar Volcanoes.


Shot Out by Lunar Volcanoes.
In the Astronomy and Astro- Physics Prof.
George W. Conkley OF the University of the
City of New York has an interesting article on
the Probable Origin OF Meteorites." Prof.
Coakley defines the wor5 meteorites as be uses
it. &c denote only those solid MISSES Of metals
or minerals which have been ascertained TO
have fallen upon the earth from some source
beyond 1t, and he particularly excludes shoot
ing stars or showers of such stars.
Prof Coakley supports the theory that the
mefeorites were originally hurled from volcanoes
on the moon, which had the power to throw
these solid bodies beyond the reach Of the
moons prevailing attraction and within the
controlling attraction Of the earth.
BY mathematical computation a point in
space is established where the attraction of the
moon and the earth are equalized. Prof. Coax
ley saws:
1.-The velocity with which a lunar volcano
nearest the earth must project body to just
reach the nearest point Of the sphere of equal
attraction, at the distance from the moons
center, equal to 23,ss4 miles. is found to be
LAB miles per second. The velocity with
which the body must be projected from a lunar
volcano furthest from the earth. on the opposite
hemisphere OF the moon. to a distance from her
center equal to 1855 miles is found to be
l,45O miles per second. But while the pro-
jectlie in the former case, thrown toward the
earth, is leaving the moons surface and drawn
back by her attraction its fight is being helped
by the eartb's attraction. which alone would
impart to it final velocity ut the surface of the
sphere. equal TO o. 1872 mile per second.
Hence the lunar volcano nearest the earth
needs only to impart the velocity LAB minus
0.292 equals 1.l5i miles per second in order to
cause the projectile to reach the surface of
equal attraction. This is only about three times
tl,a eli rit, nfO Yaaf nnv1
of cannon ball. In the opposite direction,
however. when the projectile is launched from
a volcano on the moons furthest hemisphere. if
there be any there. with the velocity Of $50
miles per second. the earths attraction helps
the moon TO bring il back with to-al impaired
velocity of C.292 mile per second. Hence the
volcano Ough: 10 impart a velocity Of ,450
plus 0.292 equals LAP miles per second in
order that the body may just reach the sphere
of equal attraction. his velocity Is only
about four ard q half tiu,es the cannon balls
maximum velocity Of 1000 feet per second.
However. it is not improbable that in this last
case the earth's attraction would help the moon
TO bring back the projcctile to her surface.
Though ii j. probable that tie moons furthest
hemisphere has been subject 10 volcanic action.
like the hemisphere nearest to Us, yet we know
nothing certain with regard to that distant
hemisphere. We shall not count on il in any
way in the theory of meteoritos. except that it
is now certain that an initial velocity OF from
three to nbont four and half times the maxi
mum velocity of a cannon ball applied in a
vertical direction to a projechle az any point OF
the moons surface would bring it TO the surface
of the sphere of equal attraction between the
earth and moon.
Every astronomer knows that the moons
nearest hemisphere is almost covered, III all
directions, by the craters of extinct volcanoes,
many of them far greater in extent than any on
the earth. 1t can hardly be doubted that the
earths volcanoes are capable OF imparting, i'll
vertical direction. a velocity three. four or
five times that Of the cannon balls maximum.
Hence these larger lunar volcanoes must be
considered capable of exerting at least an equal
force. The bodies projected from them wonld
reach the surface of the sphere Of equal attrac
ton with various velocitieS, an from all direc-
tions within 81 degrees of the moons visible
center, great circle across her Gisk. If
the greater part of these projectiles had fallen
back to the moon the interior floor of her
volcanic craters would present very different
appearance from that observed. They would
be filed up with these irregular fragments
instead Of presenting usually deeply ex-
cavated and smooth surface, only broken oc-
casionally by few small volcanic cones. the
effects, probably, Of subsequent minor erup-
tons.
The moons volcanoes must have been act
i've for many ages. though they have now been
extinct perhaps for millions OF years The ex-
plosions, which NAV have sent forth the masses
that nave faiien on the eartn, snOu!d De con-
sidered us having taken place at various per-
iods, after long intervals from the same volcano,
and also at different times and i'll various di-
rections from other volcanoes with different
situation on the moons surface. The projec
tiles should not be considered as all starting at
once from all the volcanoes but their ejec-
lions should be regarded spread over long
intervals of time. whether from the same or
from different lunar volcanoes.
Prof. Coakley shows how these projectiles
would hang in space. revolving around the
earth with orbits of different degrees of eccen-
tricity. They may, he says. continue to revolve
around the earth for many ages. even after the
lunar volcanoes became extinct, before the
suns attraction could bring their perisees SO
near the earth as to cause them to penetrate
our atmosphere. From the great number and
variety of these orbits the epochs. when their
persees should be reduced by the suns ac-
tion might readily be spread throughout the
ages. Portions of these prOjectes may have
been dropping upon the earth for many ages
past and they may continue to do SO for many
ages to come.