The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1900-11-11
THE NOVEMBER METEORS
ASTRONOMICAL STATIONS READY TO
TAKE OBSERVATIONS.
Considered Possible that Expected
shower Of Last Year VIII APP
pear This Month.


the world. is to be given up as lost. or
whether 1t mas merely been delayed a
year beyond the calculated time and will
take place in its full glory next week. The
attitude of the Harvard College Observa-
tory in this matter is probably typical of
that taken at most astronomical stations.
While admitting that the chances of the
shower appearing are less than year
ago, Professor Pickering and his assistants
have not by any means given up hope, and
though the preparations which have been
made for recording it are less extensive
than they were last November, they are
still sufficient to take full advantage of
the situation in case the shower occurs.
The November shooting stars are, Of
course, q recognized institution, and are
due on the 18th and 18th of the month
each year. They are known as the Leo
nids, from the position of their central
point in the constellation of the Lion, and
the number seen in ordinary years would
range from fifty or one hundred to eight
hundred or one thousand. The Harvard
observatory noted some eight hundred, for
example, last November. But what was
expected last year. and is hoped for next
Tuesday night. is a recurrence of the
magnificent displays which were seen IN
1893, 1888 and 1856, when not hundreds but
thousands and tens Of thousands shot into
the earth's atmosphere. In 1893 COM
petent observer in Boston calculated that
the number had amounted to 100000, seem
ing to the eye TO fall as thickly as the
flakes in q snow storm. 1t may easily be
seen how such a display would rank with
a total eclipse of the sun as the most
spectacular of the celestial phenomena.
IRREGULAR MOVEMENTS.
The interval between these great me-
teoric showers, as may be noted from the
dates just given, is thirty-three years. But
the nature OF the shooting stars is such
that they are peculiarly liable to pertur-
bations, so-called. caused by the attraction
OF the planets. Within the last 1850 years.
indeed, they have been swung out of one
orbit and into another by the influence Of
the planet Uranus. During the last period
OF thirty-three years, it seems. they nave
been especially liable to perturbation. and
some astronomers who look for the great
shower to take place next week, ascribe
the delay to this cause.
1t is necessary to understand the LeOnidS
as stream OF small particles, no larger
than grains of sand-the debris. perhaps,
or comet-howing continuously in
mighty orbit, which annually, in the mid
die of November. intersects the orbit OF
the earth. Through most of the length
OF this belt the particles are only sparseiy
gregated in a vast swarm, with relation to
which the others may be regarded only
as stragglers. The Leonids complete their
orbit in thirty-three years time, and once
in thirty-three years, therefore, when we
enter the part OF the great swarm, we may
look for such a display that of 1888 or
lSo6 in other years we see merely the
'stragglers." In time, of course, the par
ticleS Or
their orbit, since the outer ones take more
time TO complete the circuit than the inner
ones, and tend constantly to fall behind
IN the race. But this is a matter of mil
lions of years, like so many other opera
tions in astronomy.
LEONIDS ARE HARMLESS.
In passing through the orbit of Leonids
We see only the particles which are ignited
by entering the earths atmosphere, some
100 200 miles distant. No Leonid was
ever known TO reach the earth, the ter
rife heat to which they are subjected
burning them out before they have ap-
preached nearer than fifty or sixty miles
They to oe distinguished entirely from
the sporadic meteorites, which from time
to time appear as firebalIs in the sky and
sometimes fall to the earth, before they
are burnt out, in masses weighing thou
sands of pounds. A shower of such as
these would be disastrous, while the Lee
cnids are quite harmless
In the 1888 shower one observer likened
the appearance of the sky TO a vast UNI
brella- This was due TO the fact that all
the Leonids, seeming at first to be darting
in every direction in the heavens, radiated
from certain fixed center, the so-callcd
radiant, alluded to before being in the
constellation Leo. As matter of fact,
the course of the Leonids in the sky is
parallel, and the appearance of radiation
is due to perspective, as in the parallel
lines of railway track, which seem like
the Leonids to originate in a single point
The radiant, however, is only approx
mately fixed and it is an important point
therefore, to establish it more exactly
since, from the position of the radiant,
astronomers are able TO calculate the d.
rection in which the Leonids are moving
Photography, it is hoped, will do great
deal 70 settle this point Photographs
taken with the Harvard Instruments both
here in Cambridge and at Arequipa, Peru
have very satisfactorily recorded casual
meteors crossing the field of vision On
one in particular, where three shooting
stars Of a single system had been re-
corded, It was observed how exactly the
point of radiation could be defined by the
conveyance of the three paths, especially
in comparison with visual observation
of the three meteors which was fortu-
Eately made ut the same time. If next
Tuesday the great swarm reappears there
fore, and If the weather conditions are
favorable, the Harvard Observatory hopes
to secure on its Photographic plates COM
plete data for determining the radiant and
consequently the direction, OF the Leonid
swarm.
PHOTOGRAPHIC CONTRIvANCES.
Some of the Photographic appliances to
be used-always supposing the swarm re-
appears-have been especially devised for
the occasion. The most remarkable, per-
haps, is a swinging camera. for securing
stationary images of the Leonids 1t is
like the swing of pendulum-in state of
balance at either end; moving faster, COM
paratively, than the shooting star at the
middle, but at some point between. on the
rise or the fall exactly corresponding to
the velocity of the object which il is all
this time phOtographing. Besides getting
the image at rest in this way it will be
easily possible 10 calculate the speed of
the meteor by ascertaining the position of
the camera in it's swing when that image
was secured
Another interesting instrument is fitted
with prismS 10 photograph the spectra OF
the Leonids, from which IL viii be posi-
BILE 10 learn their composition. The only
spectrum OF n shooting star ever secured
by photography was obtained at the Har-
ward station at Arequipa four years ago,
and shows by its lines the presence of n.y.
drogen. Still another Photographic instru-
ment has q rotating disc over the aperture,
revolving thirty times a second. In the
disc is a hole which, passing over the aper-
ture. records the path OF the meteor in a
series of dots ANY difference in the dis