Pierre weekly free press. (Pierre, S.D.) 1889-19??, 1892-03-31
The Present Sun Spot.

Mr.. Christie, the Astronomer Royal,
informed the representative OF the
London Globe that this is the largest
spot yet photographed at the Green
wich Observatory (where the sun has
been regularly and systematically
photographed since 1879, and that
the greatest attention has been paid
TO it, with view to clear up, as
far as possible, moot points with re-
gard to the cause, periodicity, and,
perhaps, even more particularly, the
magnetic disturbance which these
spots bring about on this earth. Some
excellent photographs have been go.
cured, but, unfortunately, on several
days the gun was obscured, and un-
I'll photographs are received from In
dia or Mauritius the investigation
cannot be regarded as COM
plete. However, the informa
tion which Mr.. Christie has obtained
is OF the greatest interest and value.
In the first place, the spot is found to
be composed OF two nuclei, very black,
surrounded, as usual. by apenumbra,
or fringe, and with several smaller
nuclei, connected with 1T. Occupying
as it does an area of about 1850 Of
the face OF the sun as we see it, tue
"spot"-svill to speak OF it in the
singular numbers plainly shown on
the negatives taken at observatory;
Photographic plates ten inches square
being used, and the solar disk being
eight inches in diameter. Without,
therefore, the aid OF q magnliyingglass
the unusual size and Importance of
the spot are at once evident. But 1t
is when the negative is placed under
microscope and accurately measured
that the details Of it's size becomes
more striking, for it is found that,
while its greatest lenght isabout 1OO,-
600 miles, and its breath 10000
miles, the whole group extends over
10000 miles.
Asked as to what was the cause OF
these spots, Mr.. Christie said that
there had been several theories franz
ed to account for the phenomenon,
but none that were entirely satisfac,
tory. There were those, for instance,
OF Faye, Secchi. and Lockyer. The
theory OF the last named was that the
spots are caused by q bombardment
OF meteoric matter falling into thes sun,
and causing q great splash" The
nucleus, as the dark part IS called, is
cold, and is at a lower level than the
general surface OF the sun; while
around the spot are generally seen
what are called facul@, part OF the
SUMS surface which are raised up. Of
ten by means OF the spectroscope can
be traced moving masses of molten
matter surging round and over the
nucleus. The apparent movement OF
the spot across the face OF the sun is,
of course, the movement OF the sun it.
self carrying the so called spot withit.
On these oints Mr.. Christie was care.
full to state rnat all is conjecture; and
he pointed out, as an objection to Mir.
Lockyer's theory, that while the spots
never appear far from the SUMS cen.
ter, the nearer the spot is to the solar
equator the taste, it appears to move;
spot at the extreme limit from the
uatortakingtwo days longer to COM
plete the circuit than one near
to it. What be was able to
speak more positively upon from the
records at that observatory wac the
characteristics of the spots as they
have been observed. In this connec.
tion a very valuable series of dia.
grams have been prepared by MIR.
Ellis, both from the observations
since 1878 and from the records
prior to that year, showing not only
that the magnetic Disturbance have
been coincident with the appearance
of the spots, but that the intensity OF
the disturbance has been in exact