A solar flare is normally only visible when observing the Sun at a
single wavelength. Most modern solar flare patrol is done by observing the
Sun in the light of Hydrogen-Alpha radiation at a wavelength of 656.3 nanometres.
Occasionally, however, a very large flare will release sufficient energy
to be visible in the unfiltered light from the Sun. It was such a white
light event on September 1, 1859 that was the first solar flare ever to be
recorded (to our knowledge) by humankind. Two
independent observers, R C Carrington and R Hodgson, described their
experiences in volume twenty of the Monthly Notices of the Royal
Astronomical Society:
Description of a Singular Appearance seen in
the Sun on September1, 1859. R C Carrington.
While engaged in the forenoon of Thursday, Sept. 1, in taking my
customary observation of .. the solar spots, an appearance was witnessed
which I believe to be exceedingly rare. .. I had secured diagrams of all
the groups and detached spots, and was engaged at the
time in counting .. the spots .. when within the area of the great
north group (the size of which had previously excited general remarks), two
patches of intensely bright and white light broke out. .. I thereupon
noted down the time by the chronometer, and seeing the outburst to be very
rapidly on the increase, and being somewhat flurried by
the surprise, I hastily ran to call some one to witness
the exhibition with me, and on returning within 60 seconds,
was mortified to find that it was already much changed and
enfeebled. Very shortly afterwards the last trace was gone ..
On a Curious Appearance seen in the Sun. R Hodgson.
While observing a group of solar spots on the 1st September, I was
suddenly surprised at the appearance of a very brilliant star of light,
much brighter than the sun's surface, most dazzling to the protected eye,
illuminating the upper edges of the adjacent spots and streaks, not unlike
in effect the edging of the clouds at sunset; the rays extended in all
directions; and the centre might be compared to the dazzling brilliancy
of the bright star alpha-Lyrae when seen in a large telescope of low
power. It lasted for some five minutes, and disappeared
instantly about 11.25 a.m. The phenomenon was of too short
duration to admit of a micrometrical drawing, but an eye-sketch was
taken .. and .. the size of the group appears to have been
about .. 60,000 miles. ..
The authors also note that a magnetic disturbance was
recorded simultaneously with the white light flare observation, and also
that "towards four hours after midnight there commenced a
great magnetic storm". The first recorded solar flare is thus
probably also the first observed instance (and of course with one
event, it could only be an indication), wherein a change on the Sun
was believed to have directly influenced the environment around the Earth.
Below is a copy of Carrington's sketch to accompany his paper
of 1860. This observation was made from Redhill, England. Points
A,B,C, and D are believed to be the intense white
flaring regions.
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