The San Francisco call., 1905-03-09
Can Be Observed
With a Small
Telescope.
Seen on Eastern
Limb Of the
Great Orb.
BY EDWARD IRVING.
AUTHOR OF HOW TO KNOW tn
STARRY HEAVENS

STARRY HEAVENS
For some little time past there has
been an unusually fine assortment of
dark spots drifting across the visible
surface of our sun, as 1t slowly rotates
on its axis. Those who have been re-
Gently watching the sun with their
telescopes have been rewarded by an
ever shifting panorama of sunspots, as
one group after another came into
sight on the left or eastern limb, pass
ed in review across the disk and disap-
peared around the western edge.
Judging by previous experience, the
present sunspot epidemic will not last
very much longer The freckled face
of the orb of day is liable at any time
to change into a spotless disk of al
most uniform brightness.
1t will be well, therefore, for all who
are interested in the welfare of the
giant globe whose radiant energy
keeps our world alive to give an oc-
casional glance in it's direction with
any suitable instrument that may be
at hand. Even a small telescope pro-
vided with a dark glass will give in
teresting views of the drifting sun
spots.
Most of the spots are in irregular
groups or clusters, the individual spots
breaking out enlarging, and merging
into one another; or splitting up and
growing smaller, until they finally
close over and disappear.
The dark spots in each group are all
surrounded and connected by a less
dark shading which is known as the
penumbra. There are also brilliant
white clouds or faeuloe scattered about
in the neighborhood Of the dark sun
spots.
1t takes the sun about twenty-five
days to turn completely round on its
axis. The earth goes round then sun
in the same direction, so that If the
periods were equal, the spots and
groups OF spots would appear to go
through their various maneuvers
without changing their places to any
great extent on the suns disk. But
as a matter of fact we take a whole
year to go around the sun, while it
rotates on it's axis in about twenty
five days. Each group of spots. there
fore, if it lasts for any length of time,
comes more or less opposite our earth
every twenty-seven days, or there
about.
The visible part of the sun, on which
these sunSpots occasionally make their
appearance. is a spherical mass Of
luminous clouds, enveloping the entire
DOQH Ol the sun anu lllQluB It's QSuSS
and superheated gases from our sight.
From the intense heat and light thrown
out by this cloud-sphere it may readily
be inferred that it's clouds do not con-
sist of condensed water-gas like the
clouds which sometimes fill our earthly
skies. They consist of similar con-
densations of the dense metallic gases
which constitute the main body of the
sun beneath them. What we see of the
sun is therefore a layer of clouds COM
posed of small liquid drops of the un-
combined chemical elements, both me-
tallic and non-metallic. These drops
have been condensed, by their exposure
to the cold of outer space, from the
hot elementary gases of which the sun
is composed.
METALLIC CLOUDS.
From the globular shape and intense
brilliancy of this enveloping layer of
metallic clouds, it is known to astron-
omers as the solar photosphere or
light globe. 1t is this photosphere that
we refer to when we say that we can
see the sun.
The sunspot freckels, which occasion
ally disfigure the surface of this visible
photosphere, make their appearance
somewhat periodically, their maximum
of frequency being about every eleven
years. They are confined almost en-
tirely to a broad belt on each side of
the solar equator These two sunspot
zones correspond fairly we'll with the
earthly zones which we term the Tropic
of Cancer and the Tropic of Capricorn.
Sunspots appear to be due to violent
and sometimes cyclonic uprushes of in
visible superheated gas from the In
tensely hot interior of the sun. They
temporarily force back the clouds COM
posing the philosophers and cause them
a.
looking cloud banks. AS the ascending
gases are less luminous than the photo
spheric clouds around them, they as
sumo the appearance of dark patches
or blotches surrounded by lighter shad-
ings, with the bright photospheric
cloud banks outside.
The bright sphere which we call the
sun is about S64, 900 miles across. A
cluster of sunspots is often $4,000 to
900 miles long and wide. Single
spots are sometimes $4,000 miles across,
with a dark central nucleus 10000 miles
wide Thus a spot as large as our
world would be too small to attract
much attention, when seen from the
earth, 93,0000 900 miles away.
Sunspots are intimately connected
with the earthly phenomena known as
the aurora borealis, or northern lights.
Also with what are called magnetic
telegraph, cable and telephone systems.
The Invisible torrent of finely divided
matter which is continually elected
from a sunsoot appears to be strongly
charged with electricity. It's particles
are so extremely small that the pres
sure of light from the sun overpowers
the the solar gravitation and prevents
them from falling back to the sun
when the original impetus is exhaust
ed They therefore keep on ascending
until they finally leave the solar sys-
tenn behind.
If The sun did not rotate this finely
divided material would shoot straight
out into space like a huge fountain or
jet of steam. But owing to the solar
rotation it is bent back into a spiral
form. like that of watch spring or of
Catherine wheel.
INVISIBLE SPIRAL.
This invisible spiral of electrically
charged matter is continually enlarg-
ing. When any part of 1t strikes the
earth it produces the various electrical
phenomena already mentioned. Our
magnetic storms generally arrive
about twenty-six hours after a sun