Evening star. [volume] (Washington, D.C.) 1854-1972, 1912-06-09

IT'S surface as might be expected, is in
state of tremendous activity. Not in
frequently luminous streamers or "promi-
nences" of the rare surface gases are thrown
out with tremendous veloc1ties to distances
comparable with the radius of the sun itself,
and sunspots are frequently found in those
places where the disturbances are particular
ly great.
When examined directly with high pow
er telescope, or through the medium of
photograph on a large scale, the surface of
the SUN shows much detail. On the bright
exterior are nearly always still brighter
specks or streaks known as facula. Sun
spots usually appear as more or less round
holes, with a dark center, or umbra, and
lighter edge, or penumbra. They may be of
almost any size, from mere apparent point
of perhaps one thousand miles diameter, to
one big enough to contain our earth many
times over and measuring upward of one
hundred thousand miles across. They are
not distributed indiscriminately over the
surface of the sun, but are located in zones
lying on each side of the solar equator.
Sometimes the growth, life, and ultimate
destruction of a spot can be followed in de-
tail with the telescope. The appearance of
one is heralded by what is evidently a vio-
lent disturbance at some point on the sur
face. A sort of dark center or nucleus soon
appears, and alters rapidly in shape, so rap
idly sometimes that photographs taken only
a few minutes apart show decided changes.
Having attained definite shape, it may exist
for weeks or even months before breaking
up: but the solar rotation will have carried
it round to the opposite side of the sun in a
fortnight, and before its temperance it will
frequently have practically disappeared or
have mfr oil ar
spots. The spot, especially while forming, pre-
sents an appearance decidedly like vortex or
whirlpool, much as if vapor cooler than the
surrounding cases. perhaps, was being drawn
into the sun. A good reason, too, for believ-
ing that sunspots are cooler than the rest of
the suns surface will appear when the meth
DDS of study of the character of sunlight, as
well as the conclusions to be drawn from this
study, have been outlined.
WHEN sunlight is broken up into its pri-
mary colors, or a spectrum formed,
we find such spectrum crossed by large
number of fine dark lines called Fraunhofer
lines, showing that certain particular colors or
wave lengths of light are lacking. The num-
Der, character, and position in the spectrum
of these dark lines are the characteristics by
which we may learn great deal about the
for the positions of some of these lines indi-
cate clearly the existence of certain well
known substances in the sun-but also about
other questions of interest. Now, sunspots,
while darker than the rest of the sun, are
still extremely bright compared with any
terrestrial source, and give rise to their own
type of spectrum. When compared with
that of the bright part of the sun, it is found
to resemble it somewhat but still to possess
characteristic differences. Some of these
differences are such as are found in a study
of terrestrial sources, one of which is hotter
than the other SO we may conclude with
reasonable certainty that the spot contains
cooler gas than the remainder of the sun.
But there is much more interesting con-
clusion to be drawn from such comparison
When source of light is placed in strong
magnetic field its spectrum shows marked
changes, consisting of doubling or TRIPPING
of some of the lines, and Hale has recently
discovered these same changes in the spectra
of sunspots. This must mean that a sun
spot is the seat of powerful magnetic field
In magnetic intensity it may be no more
powerful than can be produced in the labo-
ratory with an electromagnetic; but it is of
enormous extent, covering, as even the
smallest spot does, many millions of square
miles.