Nobody knew what to call it in 1859, when the most dramatic solar storm on record shocked telegraph operators, set their paper ablaze and lit up the horizon with brilliant auroras.
Sky watchers now know the sun can belch out dozens of solar flares and related eruptions every year, including one that put electricity grid monitors on alert this month.
Bursts known as a coronal mass ejections especially can destabilize the power grid by causing vibrations in the Earth's magnetic field, as NASA explains. Those vibrations cause invisible electric currents that can overwhelm circuitry and lead to prolonged shutdowns.
Solar researchers say their challenge is figuring out which bursts threaten disruption on the scale of the so-called Carrington Event, which bedeviled telegraph operators and crippled communication systems in 1859.
In the digital age, damage to sensitive communication networks and power grids could be more crippling, although utility regulators say they are planning to toughen protective measures.
“We're vulnerable to this thing because our electrical system works at capacity. It really doesn't take much to overload,” said Carles Badenes, an astrophysicist at the University of Pittsburgh.
He said the unpredictable flares happen more often at the height of the sun's 11-year activity cycles, one of which is near its peak. Eruptions can menace power grids, telecommunications and even astronauts.
A March 1989 coronal mass ejection caused a nine-hour blackout in Quebec. One in July 2012 was large enough to worry observers but missed Earth.
The biggest eruptions can happen anytime during the solar cycle, said Bob Rutledge, who leads the federal Space Weather Forecast Office in Boulder, Colo. He said scholars predict a 6 percent to 12 percent chance of a Carrington-level disruption in the next 10 years.
During the 1859 event, named for British astronomer Richard Carrington, who documented it, the northern lights dazzled observers as far south as the Caribbean Islands, and telegraph systems picked up so much energy from the solar storm that handsets began sparking and setting nearby papers on fire.
Frank Koza, the infrastructure planning director for a regional power transmission group, said such an event today could result in blackouts in Pennsylvania, but they shouldn't last for more than nine to 12 hours.
“Don't get me wrong. Blackouts are a big deal in the power business. It's obviously something that would cause a lot of disruption,” said Koza, who works for Montgomery County-based PJM Interconnection. “But it's something we can come back from.”
PJM, which manages power distribution in 13 states, relies on detectors to monitor natural electrical currents that could trouble the regional grid.
That system has been in place since the blackout in Quebec, with additional alerts coming from the National Oceanic and Atmospheric Administration when solar activity could menace the stream of power, Koza said.
He said PJM can reduce the flow or boost voltage in some areas in a balancing act to offset solar disruption. He said he could not predict with certainty how the system might react to a Carrington-type event.
Engineers should have a better sense of that reaction in the next few years. A task force under the North American Electric Reliability Corp. is developing mandatory standards to gauge the vulnerability of power networks and prepare them for solar bursts.
Koza leads a group that's drafting the rules, which should take effect next year, he said.
Several telecommunications companies and the National Coordinating Center for Communications, a federal agency, did not comment on preparations in their industry.
Scientists agreed that there's no reason to panic but urged awareness, public education and readiness, such as having a few days' worth of food and water available in case of power failures.
The Pennsylvania Emergency Management Agency encourages people to take “an all-hazards approach to preparedness, rather than worrying specifically about solar flares or zombies or whatever other threat they might face,” spokeswoman Ruth Miller wrote in a statement.
“These are high-impact, low-probability events,” NASA program scientist Lika Guhathakurta said of the most dangerous flares.
She said they amount to a small fraction of overall solar activity, endangering technology on Earth only in very limited circumstances.
Still, Badenes said a damaging eruption is inevitable.
“It has happened before. It will happen again. It's just a matter of how long we have to wait for this,” he said.
©2014 The Pittsburgh Tribune-Review (Greensburg, Pa.)