Sequachee Valley news. (Sequachee [Sequatchie], Tenn.) 1896-1952, 1917-01-11


whether all comets turn to the sun or
not. Some of them appear to have
parabolic orbits and fly off into space,
never to see the solar system again.
But their supposed parabolic orbits
may simply be elliptical orbits OF such
great size that the few observations
which can be made of them do not dis
close their elliptical character. The
arcs of the ellipse and the parabola are
nearly the same for short distances
But there are great numbers of comets
kpownto be permanent members OF the
solar system. They accompany the sun
and its planets in its onward journey
through space. While ths orbits of
the planets are nearly circular. all
comets fly alone in greatly drawn ont
ellipses.
Some planets are satellites of the
larger planets and fly about these cold
bodies instead of around the sun. II
comet happens to come close to NAL
or planet on itsjourney toward the sun
it may be "captured" and from then
on have its orbit permanently changed
to include the planet. Jupiter is
known comets.
The comet with the shortest known
period is Enke's. This comet never
gets farther from the sun than inside
the orbit Of Jupiter. Halley's comet,
which created the sensation of 1910,
has the longest period Of all the CON-
cts classed as periodic. All the great
conspicuous comets are of nonperlodlc
class-that is, they are not certainly
known to return to the sun regularly.
The comets are the largest in size
and the smallest in mass. per unit OF
size of all known heavenly bodies
Almost every comet consists OF
bright nucleus. a coma, oil "hair
surrounding the nucleus, and long
tail The tail always points away
from the sun. The comet comes up to
the sun, goes around it with the tail
making great sweep and finally
''backs' away, facing the sun with
it's tail behind it. The nucleus, al
though it appears sometimes as bright
as a first magnitude star, is believed
to be no more than a swarm OF meter
oio particles These are evidently
bound together by a loose bond OF
gravitation.
The coma, or hairy gaseous envelope
of the nucleus, is often Of great size.
even as heavenly dimensions go. The
head of Donati's comet was 250, 600
square miles in diameter, while the
head of the comet of 1911 measured
more than a million miles through it's
greatest magnitude. As the comet
approaches close to the sun the head
seems TO diminish in size. The tail
develops as the comet approaches the
sun and head contracts. The great
| comet of t843 bad a tail more than
200, 900, 900 miles in length and the
comet of 1889 had head 20O 600 miles
| in diameter and a tail 100, 600, 900
miles long, or farther than the dis
tauce from earth to sun.
These two comets as we'll as the
great comet of 1880 pursued nearly l.
IDENTICAL paths. All three were noted
for their close approach to the sun.
The comet of 1S43 actually passed
thru the cornta and within 80, 900
! mills of the suns surface, and only
its enormous velocity of several hun
dred miles per second saved it from
actually falling into the sun. Its O.
normous tail appeared to be whirled
around the sun in about two hours
and this fact proved conclusively that
the tail could not be an actual aplen-
dage, but must bs series of emana-
tions from the head due either to the
electric repulsions of the sun acting
upon highly rarified material in the
head of the comet or the light pressure
which overbalances the effect of gravi-
ty 10 the case of PARTICLES of extreme
ly small mass.
Comets shine not only by reflected
sunlight, but by Inherent light as
we'll, and the spectroscope shows that
| they are composed chiefly of gaseous
compounds of hydrogen and carbon.
though when near the sun metallic
lines of soudium and iron frequently
appear. So highly rarified is the ma
terial composing the heads and tails
Of comets that faint stars are often OBJ
served to shine through them undim-
med even when close to the nucleus.
| The fact that the earth has many
times been involved in the tails of
comets with no disastrous consequen-