The morning call. [volume] (San Francisco [Calif.]) 1878-1895, 1893-08-07
A BIG SUN SPOT.
1t Is Visible to the Naked
Eye.
The Blot Is About One Hundred
Thousand Miles Long-HOw
Spots Are Formed.

ut may be of interest to many of your
readers" said Miss Rose OHalloran. a
well-known astronomer Of this city, to a
representative OF The CALL Yesterday.
ito know that there is at this time spot
on the sun and that it is visible to the
naked eye. 1t is nearly conferred in hello
graphic latitude, 20 deg. south. On the
30th of July 1t appeared on the east limb
Of the sun and on the 5th OF the current
month it developed into spot OF about
100. 600 miles in length. l. you should an
nounce this Humanity suggests that tile
uuwary should br warned to use cOI0red
glasses if observing it with magnifyIng
power"
1t is now generally accepted that the
sun spots are depresSions in the photo
sphere produced by downfalls of cool
material, and that chemical elements are
ioosened from the bonds which hold them
together when In the lower parts OF the
solar atmosphere.
Small meieurltes in our own atmosphere
are heated 10 incandescence by friction
that is. by the c,ncus,ion Of thelI energy
into heat. 1t is not hard to understand,
therefore. that enormous masses falling
with great rapidly through the suns
hipuiy HedtSu dtlIhS pIclc Npu'u PIo.iu'V
the spots to be seen on the suns surface.
This cool material is produced Icy the
condensation inihe upper cool regions OF
the suns atmosphere or the hot ascending
vap0rs produced at he lower levels. This
is the main source of supply Of the S o.
producing material. The formation of
SD is followed by other disturbances OF
general uaiule III the region where IL Is
observed.
AT first there are number OF little dots,
frequently in groups. Then they sud-
denly unite. forming one large spot. The
little dots are produced by small masses,
which precede the main f,ll.
The heat caused by friction with tn
atmosphere and the arrested motion
after time cool ana condrnSe. Eventually
they fall to the philosophers, producing
fresh disturbau ces.
DOwnrushes of cool material must take
place all over the suns surface. Although
the most vic lent results Of such falls are
restricted to certain regions. minor dis
turbanceS occur over the entire surface.
As>an effect Of dOwprushes. besides the
general darkenine over the edge of the
suns disk. the surface is strangely notified
Small black specks are everywhere visible.
These fine m0ttlIngs frequently take
definite directions, indicating the existence
Of powerful currents. Sometimes they are
GROUPED IN Sucil way as 10 suggest cy-
clunic swirls. When the force of the down.
rush is insufficient 10 produce the dark
spots, yelled or smuday marks are some
times present, showing only partial COM
petinn of the atmospheric operation.
The disturbance often affects large por-
lions of the suns surface, a spot having
been known of which the breadth was
140, 600 miles. In this case the commotions
were so marked that they Could be de-
tected by the telescope. 1t often happens
that the spots appear in the places occu-
pied by previous spots.
The effects Of uprushes also vary in de-
gree. Sometimes dOmes, either separate or
in groups, are seen. and that they are hot
ter than The rest of the surface is evil
denced by the bright lines of hydrogen
surrounding them.
Another degree of disturbance is called
''quet prominence" occurring in regions
where the beginning has been marked by
the dome. These prominences are seldom
higher than 10000 miles, and may re-
srmble trees. They are almost entirely
composed of hydrogen.
The greatest degree of action In an up
rush is shown by the formation of metallic
prominences, containing other substances
besides hydrogen. They mount to enor-
nous heights with great velocity. Some
ascend to height of 400, 600 miles. moving
at the rate of $50 miles Il second.