The Richmond palladium and sun-telegram. [volume] (Richmond, Ind.) 1907-1939, 1910-04-23
the TAIL Of 1 COMET
FORMED By LIGHT AND HEAT.

Travelling ~ comets 90 In very eIOn.
gated ellipses, with the sun In one OF
the foci, - the attracting point 10
called, most Of their journey II spent
IN slow uneventfulness far away from
the hearth Of the system-hearth u
just what the word focus means. They
are then small globular aggregations,
sluggish and dina little roundish
nebula In look. Such they appear
when FIRST deserted in the telescope
coming In from space, for they are
rarely seen at al until they have en-
tered within the orbit Of Mars. Dis
lance in part, but still more their own
behavior till then, keeps them hid. !.
Within this nebulosity, known as the
head. appears ~ It nears US a bright
spot. the nucleus. Suddenly there &C.
ours q complete change In the deport-
ment Of the body, one which renders
It the observed Of all observers. and in
less civilized times occasionally its be-
ing held the harbinger Of distress, dis
ease and death.
Az soon ~ the comet gets near
enough the heat Of the sun sets up
commotion within 1t. BY very's deter
mination Of the temperature Of the
unblankefed sunward side Of the moon
we are enabled TO infer that this heat
In great at the earth's distance from
the sun in spite Of the cold Of space.
This temperature Ii 353 degrees r..
And a. the comet approaches the
sun this heat must increase inverscly
a. tho square OF the distance. At half
the radius Of the earth orbit It IL al
ready four times as great above abso-
lutte zero. at q quarter sixteen times,
and 30 ON increasingly, the tempera-
ture rising into thousands Of degrees.
No wonder the comet acts as 1t does.
It ct once becomes uneasy. WAKES In
light and. ~ the spectroscope reveals.
disruptive electric discharges start In
Il which let out the Imprisoned gases.
Then begins that spectacular career Of
perihelion passage which makes the
comet 10 superb an object and for
which It pays 10 dear. The gases
which are thus thrust out from the
interior Of the separate meteorites, to-
gether with such particles Of the iron
~ are made gaseous BY the heat, fall
prey to another force besides gravita-
tiOn. This force IL the impact Of light
itself. the light emitted by the sun.
That 20 immaterial q thing az .
beam Of light can have power to move
even . pith ball ID conception not
easy to grasp. Yet there IL no doubt
Of the fact, theoretically calculated
years ago BY Clerk Maxwell from his
electromagnetic theory Of light, for the
gaseous particles proceed to b. repealed
By the sum ut enormous speed. each
behaving exactly ~ It should by math-
ematical analysis II such were the oc-
sasioning cause. Evidently the light
waves have : propelling power in the
direction Of their own motion equal
10 their own speed.
Why. then. - It that the planets be-
tray NO such effect In spite Of their
size? The answer is. because Of that
very size. Gravity acts on the mass.
4 matter Of three dimensions; the light
force on the surface Of the body. .
matter Of two. A. body diminishes
In size, therefore. it, surface bears Z
until when small enough the second
force u the stronger Of the two.
This relation II betrayed In the con-
duct Of the tail. The Imprisoned
gases. heated to expulsion on the sun
ward side Of the comet, rise toward II
In q series Of exquisite mantling en-
velopes. a. II the comets head were
yelling itself from the too ardent gaxa
OF. the sun. Then, after rising to 4
certain height. their initial impetus
overcome. they fall back. repealed by
the light waves, although still attract.
ID BY gravity, and are driven out ia
form, the tail u the comet fresh en-
velopes taking their place.
Sometimes only Z single tail Ii form
"a. but at otherA two or even three an
shot ont, and when this happens one
II nearly straight, one curved and one
greatly bent. Now, calculation shows
that the repelling force In the case Of
the nrst ID fourteen times that Of grav
nv, In the second two and two-tenthl
times, or something less, and In thu
third only about one-fifth Of gravity
But these are the very ratios which
particles Of hydrogen gas, Of the by
drocarbons and Of iron or sodium
would respectively show.
A. the comet approaches the sun thu
display becomes more violent and
more spectacular. Finer and wilder
grows the pageant, the 'hairy star
loossning its tresses. which had stood
sedately eoiled about its head amid
the depths Of space. to stream II
gorgeous CLEANS behind It AZ It pay,
lts orbital obeisance to the ruler o.
its course. It seemingly backs ava,
+ IN keeping with the etiquette to royal
". turning always its face sunwart
~ It retreats whence It came.
But It pays dearly for its display
Tho matter going to form the tail cal
never be recovered, but II driven far
thcr away. At each successive return
to the sun some Of It's mass and bril-
lance b thus lost, and this - Why tn
periodic comets. those that have mad
many visits, are such small ana IN
cousplcuous objects. II u only tn
comets Of long ellipses ana very DID
tant habit Of which the periheiios
pageant - - 0ne.-Youth's Compan
ION.
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