November 2nd, 2008

aye aye captain

The Carrington Event

A little before noon on September 1st, 1859, England's foremost solar astronomer Richard Carrington was at work in his observatory, drawing the sunspots his telescope projected onto the screen.

He was recording a particularly impressive cluster when two brilliant beads of white light appeared over the sunspots,and became blindingly bright, expanding, kidney-shapes. Realizing that this was something very new and in his own words "being somewhat flurried by the surprise, I hastily ran to call someone to witness the exhibition with me. On returning within 60 seconds, I was mortified to find that it was already much changed and enfeebled." The blaze soon faded and disappeared.

It was 11:23 - the eruption had lasted a mere 5 minutes.

What Carrington had seen has become known as the Carrington Event - a solar flare, and a flare of extraordinary brilliance at that. As the outer layers of the sun churn and rotate ( and the polar regions and equator of the sun turn at different rates - another of Carrington's discoveries), the charged plasma drags the magnetic field into tighter and tighter loops - twisting the field lines so severely that eventually they protrude from the surface, stalling convection, exposing the counter-intuitively cooler plasma below the photosphere, and causing that area of the photosphere to dim and shrink - dropping by up to a thousand kilometres and creating what we call sunspots. The loop of magnetism is so strong it splits spectral lines (the first clue to astronomers that sunspots were a magnetic phenomenon).

Enormous amounts of energy are contained in those twisted fields. And eventually the fields snap, reconnecting suddenly in a simpler configuration. And all that energy, accumulated over hours or days is released in minutes, tearing apart the plasma and flinging it out into space in a storm of radiation and charged particles in a Coronal Mass Ejection



Some of these proton storms travel at a third of the speed of light, reaching Earth in 15 minutes. Most take a little longer - the Carrington Flare's after-effects didn't reach Earth until just before dawn.

Utterly overwhelmed, the Earth's own magnetic field dumped the incoming particles onto the atmosphere, as aurora. Aurora so bright you could read a newspaper by them, and so far from the poles the red, green, and purple fireworks were visible in Cuba, Hawaii, and El Salvador.

And for the first time in the planet's history, humans had strung the world with nicely conductive telegraph lines.

Spark discharges shocked operators and set the paper on fire. Even with batteries disconnected, aurora-induced currents in the wires still allowed messages to be sent.

Of course, the Carrington Event was the first, and by far the biggest solar flare humans have ever seen, and there no way a geomagnetic storm could do something like that today, could it?

"A huge solar flare on August 4, 1972, knocked out long-distance telephone communication across Illinois. That event, in fact, caused AT&T to redesign its power system for transatlantic cables. A similar flare on March 13, 1989, provoked geomagnetic storms that disrupted electric power transmission from the Hydro Québec generating station in Canada, blacking out most of the province and plunging 6 million people into darkness for 9 hours; aurora-induced power surges even melted power transformers in New Jersey. In December 2005, X-rays from another solar storm disrupted satellite-to-ground communications and Global Positioning System (GPS) navigation signals for about 10 minutes. That may not sound like much, but as Lanzerotti noted, "I would not have wanted to be on a commercial airplane being guided in for a landing by GPS or on a ship being docked by GPS during that 10 minutes."


Keep Watching The Skies....