The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1882-04-27
Solar Phenomena and the Aurora 30
reaIls.
ApPEARANcE or AS IMMENsE sUN sPOT.


APPEARANCE OF AN IMMENSE sun SPOT.
Professor Keller, OF Allegheny Observa-
tory, writes to the Baltimore Sun as fol-
lows:
Allegheny PAL Observatory, April 49,
IL may be well at the present time TO d.
rect the attention Of your readers TO a sun
spot, the largest which has appeared for
many years, now visible upon the face OF
the sun, and which, apart from its enor-
nous size, possesses a peculiar interest
from the coincidence OF its appearance
with the brilliant aur0ral display OF
last Sunday evening, with which it Is
perhaps connected. This spot, which has
lust reached the centre of the suns disc,
may be seen with the naked eye at sunrise
or sunset, when the light is sufficiently
diminished by its passage through great
depth OF atmosphere, or at any time OF DAY
through a dark glass. Ii may also be seen
i'm the image of the sun formed when his
rays are allowed TO pass through pin-hole
and fall upon sheet OF paper at consld-
cradle distance, and has, in fact, been ire
qnently noticed here in the images
formed by accidental apertureS in the
window-curtains, &c. It's appearance,
as projected from the eye-piece OF the
great equatorial upon Il screen, Is that OF
gigantic whirlpool in the brilliant envelope
OF the sun. Long flaments OF light pro-
ject into it, curving with spiral motion
toward q central vortex, which appears
black in contrast with the dazzling bright
ness OF the surrounding surface. Numer-
Gus smaller spots surround the principal
one, and several smaller groups appear on
other parts OF the disc. The area OF the
large spot, determined from measurement
OF the image. is in round numbers a thou
sand million square miles.
Although the connection between sun
spots and the various phenomena OF the
aurora il one OF the most occult and mys-
ferrous i'm nature. that such connection
does exist has been. confirmed 10y too many
observations TO justify us i'm considering
the tremendous disturbance i'm the aCtiyi-
ties of the sun indicated by the appearance
OF this spot and the magnetic storm OF the
morning OF the 18th rs merely chance CO.
medicines. Nearly every exceptionally
brilliant aurora which has appeared has
| followed some such outburst OF solar ell
ergy. Both have probably their origin in
the same hidden cause, which remains one
Of natures deepest mysteries.
The aurora began here with the fOrma-
ton Of an arch OF bright greenish light in
the north, which disappeared about II
o'clock. when the most striking character
| istc was the great sireamers and flashes OF
| light, converging with singular fiXity to a
point some twelve degrees south Of the zc-
NTH, the bright star Arcturus passing di-
rectly through il ut twenty minutes past T..
| examined the spectrum OF the grecnish
streamers with two-prism spectroscope OF
the form used 10y Higgins in his star Oh
seryations, and found il to consist OF
brilliant yellowish green line, which
seems to be characteristic Of all aur0ras,
several fainter bands in the blue, which ap-
pear in the plates OF the Edinburgh OBJ
servationS, and very faint band in the
violet, which / have not yet been able TO
identify in any previous observation. The
rose-colored light accompanying the earlier
part Of the display did not appear with
sufficient brightness TO afford visible spec
trum. Respectfully, yours,
j. f.. KELLER,
Assistant, Allegheny Observatory.