Correction: An earlier version of this article said that the North American Electric Reliability Corp. makes rules for electric utilities to prevent blackouts. NERC develops regulations to help prevent blackouts, but the Federal Energy Regulatory Commission, which regulates NERC, must approve any such rules. This version has been corrected.

The sun is waking up.

And on June 7, it woke up Michael Hesse. At 5:49 a.m., the solar scientist received an alert on his smartphone. NASA spacecraft had seen a burst of X-rays spinning out from a sunspot. The burst was a solar flare — and a “notably large one” at that, Hesse said later.

The sun has been quiet for years, at the nadir of its activity cycle. But since February, our star has been spitting out flares and plasma like an angry dragon. It’s Hesse’s job to watch these eruptions.

If a big one were headed our way, Hesse needed to know, and fast, so he could alert the electric power industry to brace for a geomagnetic storm that could knock some of the North American power grid offline.

Hesse gathered his team at the Goddard Space Flight Center in Greenbelt, where he is chief of the Space Weather Laboratory, and fed the latest data from four sun-staring satellites into powerful computers.

At 7:49 Hesse got his answer. An animated chart traced the predicted path of a huge arc of plasma — hot gas — hurtling through the inner solar system. But only the tail of the plume would lick Earth, arriving June 9 and driving a dazzling display of the northern lights from Alaska through Maine.

While a video of the eruption captured by NASA’s Solar Dynamics Observatory showed an enormous plume spraying from the sun, this solar tantrum would not be the big one — it would not be the 1859 event all over again.

Sept. 1 of that year saw the largest solar flare on record, witnessed by British astronomer Richard Carrington. While tracing features of the sun’s surface, which Carrington had projected via telescope onto paper, he saw a sudden flash emerge from a dark spot. Although such sunspots had sparked curiosity for centuries — Galileo famously drew them, too, in the early 1600s — Carrington had no idea what the flash could mean.

Within hours, telegraph operators found out. Their long strands of wire acted as antennas for this huge wave of solar energy. As this tsunami sped by, transmitters heated up, and several burst into flames. Observers in Miami and Havana gaped skyward at eerie green and yellow displays, the northern lights pushed far south.

A knockout punch

Such a “Carrington event” will happen again someday, but our wired civilization will suffer losses far greater than a few telegraph shacks.

Communications satellites will be knocked offline. Financial transactions, timed and transmitted via those satellite, will fail, causing millions or billions in losses. The GPS system will go wonky. Astronauts on the space station will huddle in a shielded module, as they have done three times in the past decade due to “space weather,” the scientific term for all of the sun’s freaky activity. Flights between North America and Asia, over the North Pole, will have to be rerouted, as they were in April during a weak solar storm at a cost to the airlines of $100,000 a flight. And oil pipelines, particularly in Alaska and Canada, will suffer corrosion as they, like power lines, conduct electricity from the solar storm.

But the biggest impact will be on the modern marvel known as the power grid. And experts warn that the grid is not ready. In 2008, the National Academy of Sciences stated that an 1859-level storm could knock out power in parts of the northeastern and northwestern United States for months, even years. Report co-author John Kappenmann estimated that about 135 million Americans would be forced to revert to a pre-electric lifestyle or relocate. Water systems would fail. Food would spoil. Thousands could die. The financial cost: Up to $2 trillion, one-seventh the annual U.S. gross domestic product.

Utilities say they’re studying the issue, with an eye toward understanding how to protect the grid by powering down sections of it during an hours-long solar storm.

Their efforts are motivated, in part, by the sun’s increasingly frequent outbursts. Every 11 to 12 years, solar activity ramps up. After a quiet season, the sun is now spitting out flares again, with activity expected to peak in 2013 and 2014, said Dean Pesnell, a solar scientist at Goddard.

“The sun is not partisan, it doesn’t listen to diplomacy, and sanctions don’t work,” said Peter Huessy, president of GeoStrategic Analysis. Huessy wants Congress to enact rules that would force power companies to better protect the power grid. “The sun has its own clock. And we don’t know what that clock is, except for once every hundred years or so, it has a coronary.”

Running out of time

Predicting flares is still a nascent science. They typically spring from sunspots, which appear when tangled magnetic fields well up from deep within the sun. A burst of X-rays, flares travel at the speed of light, reaching Earth in about eight minutes. While they can interfere with the electronics in satellites, they pose no direct threat to people on the ground because Earth’s magnetic field acts as a shield against this type of solar weather. This shield is weakest at the North Pole and South Pole, which is why space weather affects high latitudes the most.

Within hours of a flare, the sun often tosses in an encore: a huge plume of plasma known as a coronal mass ejection. During each solar cycle, the sun throws off hundreds of these. But only a few are large. The fastest, most damaging of these waves of charged particles can reach the Earth in about 20 hours. On arrival, these storms deform the Earth’s magnetic field, charge the atmosphere and induce electric currents in power lines for several hours.

But estimating the arrival time and damage potential of such storms is tricky business. The simulations that Hesse runs at Goddard provide only a rough estimate, bracketing the arrival time of a solar storm in a 12- to 14-hour window.

More-precise alerts are sent to power companies just 20 to 30 minutes before a solar storm hits Earth. In May, 29 such alerts went out, triggered by a NASA satellite called the Advanced Composition Explorer, or ACE.

But if ACE fails, the space weather warning system will be crippled, said Tom Bogdan, who heads the Space Weather Prediction Center at the National Oceanic and Atmospheric Administration. Bogdan wants Congress to fund other satellites to replace ACE before it runs out of fuel in 2021.

An uncertain fate

One possible replacement, a satellite called DSCOVR, sits nearly finished in a hangar at Goddard, where it has languished since 2001. The vision of Al Gore, sidelined when congressional Republicans defunded its launch vehicle, DSCOVR would provide longer warning times for solar storms. Its fate is uncertain, although President Obama is expected to ask for funds to launch the probe in his 2012 budget. Bogdan said the earliest it could get off the ground is 2014.

Representatives of the power industry take issue with the worst-case scenarios.

Leaders do acknowledge that huge solar flares are a serious issue, one the industry is addressing. But “the idea of 130 million people out of power for 10 years is an overstatement,” said Gerry Cauley, president of the North American Electric Reliability Corp., or NERC.

In 2007, Congress gave NERC the power to develop regulations — to be approved by the Federal Energy Regulatory Commission — for electric utilities to prevent blackouts like the one that left an estimated 50 million people in the Midwest, the Northeast and Ontario without power for up to four days in August 2003. (That outage was caused not by a solar flare but by high demand and a tree that fell on a power line; a cascading failure knocked some 100 power plants offline.) “The potential is there for damage to equipment and possibly even outages,” Cauley added. “But the grid itself is very resilient.”

The grid’s weak spots

In 1989, the grid got its most severe solar test, and sections did not fare well. A solar storm one-tenth the strength of the 1859 event triggered a cascade of failures in Quebec in just 90 seconds. Several million people went without power for nine to 12 hours, causing hundreds of millions of dollars in damage. In South Africa, the storm destroyed huge transformers.

Each the size of a house and costing several million dollars, transformers are the grid’s weak spots. They boost the voltage of electricity for transmission along high-voltage lines, but they also absorb extra loads coming down those lines. During the 1989 event, two of South Africa’s transformers overheated and fried during the storm, while nine more failed within a year, said Mark Lauby, a vice president at NERC.

Legislation under consideration in the House would force utility companies to protect 350 critical transformers from a massive solar storm. Under the bill, called the SHIELD Act, the one-time cost of $100 million to $300 million would be passed on to customers. Last year the bill passed in the House unanimously, only to stall in the Senate.

But the SHIELD Act is not dead. In May, the subcommittee on energy and power held a hearing on the bill, where military officials and government regulators warned of the dangers of space weather. Advocates expect the legislation to be reintroduced.

In the meantime, Bogdan will be losing sleep over losing ACE, the sun storm sentinel.

“It’s the extreme solar events I’m worried about,” he said. “It might not happen this solar cycle. But sometime in my lifetime or my children’s, that storm will be here. The question is ‘Will we be prepared for it?’ ”