The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1898-09-04
COMETS NOT SCARCE.
The Crop This Year Promises to Be
a Large one-Astronomers Are
Pleased.

E1cdSSQ.
Within the last few weeks no less
than four comets have been reported.
three of the number having been first
seen at the Lick observatory, says the
New York Tribune. These, with the
two discovered earlier in the year,
make the score for 1898 an unusually
good one, considering the fact that
only six months have elapsed so far.
In January, Winneck'S comet, a vet
eran that has been known to the as
tronomers for nearly a century. and
which comes in from the outer regions
of the solar system to circle around the
sun every SIS years, was perceived by
Mr.. Perrine, Lick observer, and re-
ported TO the fraternity of star gaZers
by telegraph. Then, in March, another
one, probably a new one. was seen by
the same man. Two or thre weeks ago,
two more little fellows, also new, were
picked up at Mount Hamilton Almost
at the same time EnckS comet was
first seen on its way back to the sun by
New South Wales astronomer. And
a week ago, Mr.. Hussey of the Lick
observatory staff, spied VOLTS comet,
inward bound.
In two important respects this class
Of bodies differs from the others which
belong to the solar system The orbits
OF the planets are nearly circular, al
though they all show a tendency to-
ward ellipticality. But the cOmetary
orbits are exceedingly long and narrow.
When one is true ellipse, the comet
will come back to the vicinity OF the
sun, that is. if nothing happens to ii in
the meantime If the path which it de-
scribes when it makes its first visit to
the center of the system is parabolic-
an open curve-then it cannot be eX-
pected to return unless something I'M
usual happens which alters the form OF
the orbit. This something is almost in
variably an experience with the at
tractive influence of Jupiter. If the
comet should cross the latter's orbit
when the giant planet was in that
neighborhood a change in the curve of
the cometary orbit would be effected
In many cases a comet which might,not
otherwise have been seen again is thus
entangled in our solar system. There
after the astronomers speak of 1t as
belonging to Jupiters family of COM
cts.
In the next place, this class of bodies
is Of the gauZieSt imaginable texture
Some of the planets are composed OF
slightly lighter material than the eartn,
but the comet Is lighter than the air.
II has been estimated that the mean
density of most comets is about the
rine-thousandth of the atmosphere at
sea level. As the inner part OF the glo-
bular nucleus is somewhat condensed,
the outer portion must be below the
average in density. The precise degree
of it's tenuity 1t is hard to conceive
Moreover, accustomed as we are TO the
resistance offered by the air to the rap
id movement Of a cloud Of dust here
on earth, 1t is not easy to understand
how a comet can fly through space at
the velocity which characterizes It's
flight, nor how it keeps together.
Most of the comets which are dlscoV-
ered-fuIly four out of every hve-afe
so faint that they can be seen only
with a telescope. That is true, for IN
stance, of the six thus far observed this
year. And yet, even these telescope
comets are anywhere from 1OOVO 10 ~
900 miles in diameter.
Professional astronomers are always
peculiarly tickled by the discovery OF a
comet. If it be an entirely new one,
they compute it's orbit carefully and
begin to speculate on the probability
of its return. If it is an old stager
they compare the time and place OF us
temperance with the predictions made
from former appearances; and if there
is any discrepancy they examine tur-
Their to see whether this is due TO an
error of calculation. or whether the
comet has encountered something in
its last outing which has permanently
affected its character for promDtness
and dispatch.
HALLEY'S COMET.
The first comet whose return was
predicted was that which bore the
name of the astronomer who made the
forecast, HALEY. This, by the way,
is the comet which goes far beyond the
solar system on it's journey away from
the sun. HALEY made his historic pre-
diction in 1852, and he had been dead
over a dozen years when, in 1S5S-os, 1t
was fulfilled. The next comet whose
return had been similarly predicted
was Encke's. which was sighted atresh
only a week ago in New South Wales.
This is a short period comet, requir-
ing only 3.3 years to make its entire
circuit. After it was seen in Novem-
her. 1918. Encke identified it as one that
had been discovered in 1856. 1t has
been circulating in the solar system,
therefore. for over a century.
ENCKE'S AND VOLTS.
There is another fact in regard TO
Epcke's comet which renders 1t IN
teresting. The astronomer whose name
it bears discovered, after three or four
returns. that its period had been short
ened perceDtibly. And at the time OF
his death, in 1865. he estimated that the
period was 16 days shorter than 1t was
in 1878. He inferred from these obser-
vations that the resistance offered by
the ether which fills all space had been
sufficient to produce this effect. one
would naturally suppose that resistance
would retard the return of comet, out
the physicists say otherwise However,
there are two reasons Cor susoecting
that Encke's explanation of the short
ening of this comets period was lncor-
rect In 1865 the amount Of accelera-
ton had been diminished, and no such
effect was ever noticed in the case OF
any other comet. Professor Young, of
Princeton. suggests that Encke's comet
encounters a cloud OF meteOric matter
at intervals. and that this hindrance
is indicated by the shortening of its
period.
SWIFT'S IS EXPECTED.
There is another short-Deriod comet,
one discovered by Swift late in 1889,
that is expected to return this sum-
nter. 1t has never been seen but once.
but from its orbit its period was esti-
mated at 1884 years. Occasionally
wanderer of this class AN astronomical
vagrant. fails TO turn up a second time.
and its failure to do so gives rise TO
muCn SpeculdIlOn IL oNlAl 1909 SOAANS
disappoints the astronomers, therefore,
it will not be the first case OF that
kind.
The comet which TemDel discovered
in 1867 is one of these uncertain guam
titles. 1t has not been seen since 1873.
and little hope is now cherished that
it will ever turn up again It was due
this year: and Denning, an English ex-
pert in such matters. estimated that It
would appear. if at all, near the star
Beta Leonis, early in June The chance