New-York tribune., 1921-06-12
Fireworks Expected june 26
AS Sky Visitor Passes the Earth
lhls Planet May Penetrate Swarms of Meteors Tha
Trail Comet and Result Will BE Inter-
esting but Not Serious

| OF the earth'S orbit at point near the
earth that the encounter Of the earth
with the meteors can occur.
Last Tuesday the Pons-Winnecke
comet made its nearest approach to the
earth. The comet was then some dis
tance above the plane in which the
earth's path lies and no encounter of
| the earth with meteor swarms was pos.
slble. Tomorrow the comet passes its
| point of nearest approach to the sun
or perihelion, 1t is then less than two
million miles beyond the earth's orbit
but still some distance above it's plane
and more than thirteen million miles
distant from the earth which has been
| gradually falling behind the comet.
On June II the comet crosses the
plane of the earth's orbit, passing from
| a point above it, or from the north, to a
point below it, or to the south. At this
point the comets path comes within
about one hundred thousand miles of
the earth's path. This is the point of
nearest approach of the two paths-not
OF the two bodies. 1t is here that as
tronomers hoped that close approach
of the comet to the earth might occur
but the comet is ahead of the earth by
about nine days, since the earth will not
reach. this point until June 25 or 26. 1t
will then be some twenty million miles
behind the comet, which, having passed
its perihelion on the 18th of June is
once more headed for regions far be-
yond the earth.
When the earth reaches this point on
June 90 or &c, however, extensive
swarms of meteors may be passing in
the wake of the comet. Some of these
meteors may become enmeshed in the
earth's atmosphere and a fine display
of noiseless fireworks may result.
Though there are excellent chances
that an encounter between the earth
and the meteors will take place here,
there is necessarily some uncertainty
on this point Meteoric swarms may
not be passing at the time that the
earth reaches this point and when the
earth has passed on beyond the cross
ing point and the two paths are again
in different planes no encounter can
take place. Sometimes the densest por
tions of a meteoric swarm are ira
versed in very few hours. A fine dis
play might be visible in Europe, for in
stance, while only a few stragglers
would be visible in California a few
hours later. Clouds, Of course, would
destroy the chances of seeing any dis
play at all and bright moonlight would
dim it's splendor. Fortunately the
moon is at the last quarter when the
earth reaches this point and so would
not interfere with the visibility of any
display until after midnight.
shooting Stars" Always
Are Noiseless Visitors
Meteors, or, as they are sometimes
called, Shooting stars" are always
noiseless visitors. 1t is very rarely that
fireball or decorating meteorite ap-
pears among the meteors that travel in
swarms in the orbits of comets
The denser portions of the nucleus Or
head of comet probably consist chiefly
of larger meteoric stones, which would
not be so noiseless if they should pene-
trate the earth's atmosphere. The
sharp reports and explosions and bril-
liant flashes of light that attend the
passages of freballs or meteorites
through the earths atmosphere are
produced by the rapid fight of these
stones and the great heat of incandes-
cence produced when the stones are
slowed down by friction with the air.
The individual particles that belong
to a meteoric swarm probably do not
exceed few grains in weight. They
are mere non-luminous grains of sand
until they penetrate the earth's atmos-
phere at high speed and are heated to
incandescence by friction with the air
1t has been estimated that any meteor
weighing less than ten pounds before
its encounter with the earth's atmos-
phere would be completely consumed
by friction before it could reach the
earth's surface.
Upon a few occasions when the
earth has encountered dense portions
OF meteoric swarms, as happened, for
instance, on November IL, 1888, when it
was estimated that at least two hun
dred and fifty thousand meteors were
visible at one place within five or six
hours, there has been no sound attend
ing the silent display of fireworks and
no particles have been seen to reach
the ground. Such rare displays have
been compared to the fall of snow
fakes, for the numberless particles of
incandescent light are as noiseless in
their flight as fakes of snow.
The P6nsWinnecke comet was dis
covered at this return photographically
by Professor Barnard at the Yerkes
Observatory on April 10. 1t was then
very faint and visible only in large
telescope. Since that date it has been
observed continuously and it's orbit has
been carefully recomputed, taking ac-
count of all the disturbing factors that
have affected its motion since it's last
appearance in 1915. 1t is hardly ex-
pccted that the comet will be visible to
the naked eye at its perihelion passage
tomorrow, or that it will have a tail
OF any appreciable length, since it ap-