Monday, June 25, 2012

Space Weather - The Carrington Event

In August of 1859, during historic Solar Cycle 10, something very strange began to happen. The Sun, as it neared solar max, grew unusually active. It produced prolific numbers of sunspots and flares, some of which were visible to the naked eye. This continued through the end of the month, until, just before noon on September 1, British astronomer Richard Carrington, just 33 and already acknowledged as one of England's premier solar astronomers, observed an incredibly brilliant solar flare – a flare that was easily visible to the naked eye. In later times, this single flare became known as The Carrington Super-Flare. In his own words from his scientific records:

“...Within the area of the great north group [of sunspots]...two patches of intensely bright and white light broke out...My first impression was that by some chance a ray of light had penetrated a hole in the [projection] screen...for the brilliancy was fully equal to that of direct sun-light; but by at once interrupting the current observation, and causing the image to move by turning the R.A. [right ascension, an astronomical coordinate akin to longitude] handle, I saw I was an unprepared witness to a very different affair...The instant of the first outburst was not 15 seconds different from 11h 18m Greenwich mean time, and 11h 23m was taken for the time of disappearance [from the telescope's view]. In this lapse of 5 minutes, the two patches of light traversed a space of about 35,000 miles...”

British amateur astronomer Richard Hodgeson also observed it; Balfour Steward at the Kew Observatory noted a “crochet” effect on the observatory's magnetometer. (A “crochet” is also sometimes called a Sudden Ionospheric Disturbance, or SID. It is when a solar event produces an abnormally high plasma density – remember, plasma is like the stuff in your fluorescent lights – in one layer of the ionosphere. This in turn creates literal electric currents running through the ionosphere, which magnetometers pick up. It creates something of an invisible lacy pattern in the atmosphere, hence, I suppose, the term “crochet.”)

And all of the previous flares and coronal mass ejections had fairly effectively cleared the interplanetary medium between the Sun and Earth.

The enormous coronal mass ejection produced by the super-flare slammed into Earth in only 17 hours.

The resulting effects lasted several days.

What kind of effects?

Worldwide aurorae for starters. These aurorae were most noted in the Caribbean, where they had never been seen before. Colorado gold miners, awakened by the brightening skies, got up and began cooking their breakfasts, because they thought it was dawn. In Europe and the northeastern United States, newspapers could be read by the light of the aurorae.

Speaking of newspapers, the Baltimore American and Commercial Advisor spoke of the ongoing event in poetic terms. “Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights. The phenomenon was very similar to the display on Sunday night, though at times the light was, if possible, more brilliant, and the prismatic hues more varied and gorgeous. The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested. Between 12 and 1 o'clock, when the display was at its full brilliancy, the quiet streets of the city resting under this strange light, presented a beautiful as well as singular appearance.”

Those dealing in the business of telegraphy did not think so highly of the display. The incredibly intense event, a maximal G5 and S5 by any definition, created induced currents in telegraph wires that were simply impossible to control. Lines and pylons threw sparks, telegraph batteries were blown, telegraphers received severe shocks, and telegraph “flimsy” paper burst into flames.

And yet some telegraph systems continued to function, despite having no batteries to power them. The induced current was simply that strong.

This was the Carrington Event, the most powerful solar/geomagnetic storm ever to occur in recorded history. It was before the advent of electricity, or electronics, or integrated grids and networks, save for telegraph systems, with which it wreaked havoc. Imagine what effect it would have today.

Dibs on the story.    ;-)

-Stephanie Osborn