The sun. [volume] (New York [N.Y.]) 1833-1916, 1910-08-14

high Temperature and subjected % enor'
| nous compression our know Iedg- 81
it, mean denaity 10 the only experimental
fact known 20 us regarding it, internal
nature. All thar remains tn be told about
| the sun concerns it, surf lC~. which sends
radiationa tn us and these radiahon-
constitute actually the solo intermediary
between us and planetary space. fortu-
natsly there are many methods for exam
ming them.
Our know ledge Of IN. sun. however
! owes il chief progress to the direct tele-
soopic study ~ the mminary's surface.
We find that this surface. far from being
uniform. appears on the contrary irreg-
ular and undulating But It ia the sun
spots which form the most strik ing feature
Of the solar disc Their formation and
changes are sometimes slow and sometimes
discOncertingly rapid Only one eNplanA-
tion can account for all the details Of their
movement the luminous surface Of tn"
sun rotstes as "A whole round an axis
~ bach is the line betwc zen the poles Of the
sun. the period Of rotP tion being about
twenty five and half dsys From
careful obserN alton of the spots We have
acquired the gertrude that the bright
external surface Of the sin IL fluid and
ne~ reasons for considering that the same
Is true Of the central regions With tn.
aid OF the spectrOscopc Ne arrive at tho
conclusion that the external radiant sur
face does not form n coherent Whole. and
therefore We can only conceive u tn be-
formed OF very tenuous paTt lCles ais-
pended IN a gaseous mass, whore they act
IN the same manner a. the carbon dust in
a candle fame Moreover We find that
the centre ~ the solar disc IL five times
more luminous than the periphery. and
that the color OF tho edge of the orb IL
distinctly reddish Wear. brought "a adj
init the existence Of a gaseous atmosphere
surrounding the radiant external surface
or photospherr. and that IN" photns phsre
again il surrounded by cooler Ebsorptiv"
gaseous layer called the Chromospherr,
containing in addition TO hydrogen tn"
vapors Of numerous elements. This
Choromosphcrc. about sWO kilometers
IN mean depth - IA fiat a. tn" sea IN some
places in others IL 10 covered with luminous
filameDts. like bright hairs. all pointing
in on" direction at least az the same time
and IN tho saiae region Elsew here II
towers above the general Lowell in mon
strous HEAPS callei prUtuberanC''s
IL Is now certain that tn" spots and
the protuberances are both in general
simply two aspects Of a single disturbance
and the surface is never at rest even when
there are no eruptiuns. The study II
the protuberanC~s and II the corona
or glow surrounding the orb during
eClipsa-. especially Of the corona. cunsti-
tutes at times Il total eClip~e one 10 the
principal occupations of physicists and
astronomers. Perhaps little will ~ left
a century hence ~ all our theories. because
the solar problem il being Investigated
with great energy. What Is more. every
new thing found IN the heavens checks and
enriches the discoveries already made
concerning the sun. We know however.
that there IL nothing in it, sil'. its position
or its motions TO constitute u world
apart. and spectrum analysis shows -
that the same elements are found IN all
the stars. IL 10 therefore legitimate 10
s,.eN from the nebulE an iiat 81 IN" suns
past ami even 20 attempt II forecast
it, future from the present state " the
extinct starr which wander over IN" path
way ~ the heavens. Eclipses. TO which
the author devot~s chapter. throw light
'paradoNicAllyl upon the problem - the
sun as we'll as NJ the moon.