Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-10-30
SPOTS ON THE SUN
THEIR NATURE, PERIoDICITX
AND ATTENDANT PHENOMENA.
The Present Outbreak the Most For
midable One Observed for
Many Years.
From the New York Tribune.

From the New York Tribune.
Within the last few days astronomers
| have reported the most formidable outbreak
| of spots on the sun that has been observed
| for several years. In a chain that is esti.
mated at 17S.OOO miles long and nearly co..
600 miles wide. and that lies nearly parallel
| with the solar equator. are a dozen large
| patches and many small ones. Inasmuch
as the suns diameter is approximated S6Os
900 miles the disturbed region extends about
| one-eighth Of the way from edge TO edge.
| The head of the procession came into view
| by the rotation of the sun about October or
5. and the tail OF 1t was not seen until two
| days later As the sun takes about twenty
| seven days to make one complete revolution
! on its axis. the rear end of the train has
! disappeared at least for a fortnight. Per-
| haps the group may reappear at the begin
ming of November.
| When number and size are carefully tab
| ulated 1t is found that there irregular
periodicty in the development of spots. the
maximum abundance occurring at intervals
| of about eleven years. The last three stages
| OF this character were reached in 1870, 1884
and 1894. From these dates one may ex-
pect the next one I'm 1904 or 1896. The mini
mum stage does not occur just half way be-
| tween the maxima. The rise from scarcity
| to abundance is apt to be more abrupt than
| the decline. According TO Tacchini. a we'll
| known Italian authority on solar phenom-
| ena, the last minimum occurred in 1900 One
| of the most important groups observed prior
| to that time was noticed in September, 1893.
| and 1t had sufficient vitality to last through
| three rotation periods of the Some
| Of the spots were visible on the naked eye
| Through smoked glass; as late in the year
| as November. At no time was the area OF
| disturbance more than about 5000 miles
| long and 5000 broad, SO that it was infer
| Tor to the one recently reported. Since the
| disappearance of spots in 1900 several OF
| moderate proportions have been reported.
| but nothing comparable with the latest out
| break.
Its Composition.
A sunspot is usually made of, two per-
| ceptible parts. dark central portion moro
| or less irregular in shape. and a grayish
border. or penumbra. When it first appears
| it undergoes more less change of form
| and perhaps grows perceptiby I'm dimen-
| sions Additional spots. much smaller than
| the principal ones. often break out few
| days later in front or behind them. At this
| time the forces which cause them are I'M
| questionably most active. After few
| days. or weeks at the most. the little spots
| disappear entirely and the large ones cease
| to bctray any alteration of form, though
| there may be a slow shrinkage in size The
| activity originally created has then SUBJ
sided and slow filling up of the spot short
| ly follows.
| The nature of a spot may be partly under
| stood If one first recalls the principal en-
| velopes that surround the sum- To all in
| tents and purposes the foundation is lumi-
| nous cloud shell. the philosophers. which is
| thought to be 1900 miles deep. and which is
| the chief source of light. Its composition
| is not fully known. but the suspician is en-
| tertained that it is made uD mainly Of car
| bon or some other highly refractory SUBJ
| stance in the form of vapor and made in
| candescent by heat. Above this surface lies
| a thin stratum. containing a great variety
of elements. and called the reversing
because a vCh
produces on the spectrum. Third, there is
| a sea of reddish gas mostly hydrogen, out
| of which rise number of enormous clouds
| or protuberances. Finally. there is the CO.
roma which seems to be partly gas and
| partly dust. and which has nebulous extern
sfons that have been traced by photography
to distance of over a million miles, much
| more than a solar diameter
1t Is now almost universally agreed that
| the spot is a huge shallow cavity in the
! lowermost of all these envelopes. At ono
time it was thought that opening was
| effected in the photosphere from below by
| volcanic action and that the spot was the
| crater. The latest view is that ii is the pro-
| duct of falling material. elected elsewhere
| and condensed by cooling while in the upper
| regions of the solar atmosphere. To this
general conception. advanced by Secchi,
Young proposes slight modification. The
Princeton astronomer suggests that the
| spots may be caused not by the downward
| pressure of such material from above, but
a local subsistence of pressure underneath,
being. so to speak sinks in the photo
sphere
Violent Action From Below.
Other evidences Of violent action from BE-
low are afforded by the numerous but COM
paratively gentle upheavals of the hydrogen
sea into ''protuberances and rarer, but
much fiercer explosions, which eject metal
lie vapors to enormous elevations with in
credible velocities. These are called ''erup-
TONS" to distinguish them from other va
rietes of prominence. They often rise TO
| height of 10000 10000 miles, and some
times reach elevation three or four
times as great From their shape and mo-
tion-the latter occasionally being 1oo miles
a second!-it is easy to see that they rep
resent elected matter. 1t is significant. too,
that they are seen only in the vicinity of n
spot Still another phenomenon seems 70
be a product of explosive action Here and
there are numerous small patches brighter
than the rest of the solar surface. Ii was
long believed that these 'faculae were
portions of the philosophers, lifted to an
unusual elevation by some force acting
from below, and made conspicuous by par
tial emergence from the faint obs1uraton
of layers above the cloud shell. That no
ton is now less generally held. Astrono-
mers at present incline to suspect that
these are floating clouds of calcium and
other luminous material, which at some
time or other was probably elected from
the interior of the sun.
1t may be added That, whlle the CORE
spondence is not precise. there is a general
harmony between the abundance and size
of spots, faculae, protuberances and erup-
TONS 1t is also to be noted that the form
and dimensions of the corona, the outer
most envelope of the sun. undergo such
changes that one type is now characteristic
of the minimum stage and another of the
maximum.
Just what takes place inside of the sun
to produce all these outward man festa-
lions is uncertain. That body is globe
of gas, compressed to a density greater
than that of water, but not lquehed, and
1t is intensely heated. The notion that
chemical forces are at work there is the
most plausible, perhaps. but it is not alto
gether satisfactory. 1t does not seem to
explain everything. AS for the per. odicity
of solar activity, that is an even greater
mystery.
Among the terrestrial phenomena whose
relation to fluctuations in the condition of
the sun is undisputed are the hysterical dis
turbances of the magnetic needle and tele-
graph wires which are sometimes observed