The Saint Paul globe., 1900-11-11
THAT NEIt(RIG SHOWER
AsTRON 0F5GRs WONDERING If THE
ONE DUE LAST YEAR WILL
COME THIS
NovEMBER's USUAL DISPLAY
What the LeOnids Are Actually Like
Some Showers OF Former
Years-PhOtOGraphi
Shooting. Stars.


ial.)-The most interesting astronomical
Question just now IS whether the great
meteoric shower which was due in No
vember of last year, but which did not
then appear, much to the disappointment
of astronomers. all over the world, is
to be given up as lost, or whether it
has merely been delayed a year beyond
the calculated time, and will take place
in its full glory next week The atti-
tude of the Harvard college obserVa-
tory in this matter is probably typlcat 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 assist
ants have not by any means given up
hope, and though the preparations Whlch
have been made for. recording it are less
extensive than they were last NoVem-
ber, rthey are still sufficient to take full
advantage Of the situation in case the
shower occurs.
The. November shooting stars are, of
course, a 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,
end the number seen IN ordinary years
would range from fifty or 100 to SOO or
1000 The Harvard observatory noted
some SOC, for example, last November.
But what was expected last year, and s
hoped for next Tuesday night, IS a
recurrence OF the magnificent displays
which were seen in 1889, 1888 and 1855,
when not hundrers but thousands and
tens of thousands shot into the earth S
atmosphere. In 1888 a competent obserV-
er in Boston calculate that the number
had amounted to 240,0O0, seeming to the
eye to fail as thiclSy as the flakes in
s1xr1 10N
such a display would rank with total
eclipse of the sun as the most spectacu-
lar of the celestial phenomena.
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
perturbations, so called. caused by the
attractions of the planets. Within the
last 1890 years, indeed, they have been
swung out of one orbit and into an
other by the influence of the planet
Uranus During the last period Of thirty
three years, it. seems, they have been
Especially liable to perturbation, cnd
some Astronomers who look for the great
shQSyers to fake place next week, as
sriheatAe delay TO this cause.
p 1t IS necessary to understand the Leo
nids asia stream Of small particles, no
larger 8ban grains of sand-the debris,
ly II}raSInis hty. orbit, which annually, in
the middle of November. -intersects the
orbit of the earth. Through most of the
length of this belt the particles are only
sparsely, scattered, but in one place they
are cCngregated In vast swarm, with
relation TO which the others may be re-
garded 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 as that of 1888 or 1866. In other
years we see. merely the 'stragglers." In
time discourse, ,cthe particles will be scat
tered more evenly through 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 q matter of mil
lions of years, like so many other opera
tiOns in astronomy.
In passing through the orbit Of the
Leon'ds we see only the particles which
are ignited by entering the earths at
moSphere. some 100 or 200 miles distant.
No Leonid was ever known to reach the
Sarth. the terrific heat to which they are
subj&cted burning them out before they
have app4 oaChed nearer than fifty or six
dy miles. They are to be distinguished
.entireiy from the sporadic meteorites
which from time to time appear as fire.
the earth before they are burnt out in
masses weighing thousands OF pounds A
shower OF such as these would be disas-
trous. while the Leonids are quite harm
less.
In the 1888 shower one observer iIkened
the appearance of the sky to a vast um
breila. This was due to the fact that all
the Leonids, seeming at first to be dart.
Ing in every direction in the heavens, ra-
dated from certain fixed center, the So
called radiant, alluded to before as being
in the constellation Leo. AS a matter of
fact the course of the Leonids In the
Sky is parallel, and the appearance of
radiation IS due to perspective. as in
1.-THE parallel lines of a railroad track
which seem like the Leonids 10 originate
In single point The radiant, no Herer
is only approximately fixed; and it is an
important point therefore to establish il
more exactly, since, from the position
of the radiant, astronomers are able to
calculate the direction in which the Ie-
Onids are moving. Photography, it Is
hoped, VIII do a great deal to settle this
point. Photographs taken with the Hlr-
ward instruments, both here in Cam
DrlGge and at Arequipa, Peru. have very
satisfactorily recorded casual. meteore
crossing the field Of vision. On one in
particular, where three shooting stars
of a single system had been recorded. II
vas oDSeLNSu now exactly the point OF
radiation could be defined by the converg-
ence Of the three paths, especially In com
parison with visual observation of the
three meteOrs which was Fortunately
made at the same time. If next Tues,ia Y
the great swarm reappears. therefore
and If the weather conditions ara favorai
bic, the Harvard observatory hopes to Sc
i5cure on its Photographic plates conap:ete
data Tor determining the radiant. and CON