Sun's 'Perfect Storm' Narrowly Missed Earth, but Could Have Wreaked Havoc

A powerful 2012 solar storm sent a huge magnetic cloud speeding through space at 2,000 kilometers per second, some four times the speed of a typical burst of solar energy known as a coronal mass ejection (CME). New research has revealed details of the powerful storm and provides a stark warning: Had the storm occurred just days earlier, it would have hit Earth directly, causing a severe magnetic storm that would have wrecked Earth's electrical grid, disabled satellites and GPS, and caused untold electronic disruptions.

Writing in the journal Nature Communications, a team of US and Chinese researchers report that this CME, had it hit Earth, would have been equivalent to the Carrington Event of 1859 - the largest magnetic storm ever reported on Earth.

"Had it hit Earth, it probably would have been like the big one in 1859, but the effect today, with our modern technologies, would have been tremendous," said University of California, Berkeley research physicist Janet G. Luhmann, who is part NASA's STEREO (Solar Terrestrial Observatory) team. The STEREO spacecraft was used to detect the magnetic storm.

The July 22, 2012 solar storm was so powerful, the researchers report, because it was triggered by two individual CMEs that occurred only 10 or 15 minutes apart - nearly simultaneous in terms of solar storms. The energy of each CME is equivalent to about 1 billion hydrogen bombs, the researchers said.

The tremendous speed at which the dual CME hurled through space was made possible because of another CME four days earlier, which cleared the path of material that would have slowed it down.

"In a sense, this was the 'perfect storm'," said study co-author Noé Lugaz of the University of New Hampshire. "The first, fast eruption greased the skids for the quick propagation of the subsequent, extremely fast eruptions through interplanetary space."

The storm narrowly missed Earth, but had the eruption occurred just nine days earlier, when the ignition spot on the solar surface was aimed at Earth, it would have hit the planet.

Luhmann said that one reason the storm was so dangerous, aside from its speed, was that it produced a pronounced and southward-oriented magnetic field. When this southward field hits Earth's northward magnetic field, the merger is violent.

"These gnarly, twisty ropes of magnetic field from coronal mass ejections come blasting from the Sun through the ambient solar system, piling up material in front of them, and when this double whammy hits Earth, it skews the Earth's magnetic field to odd directions, dumping energy all around the planet," she said.

Although storms like this are rare, the narrow miss underscores the importance of understanding solar weather events and being prepared for them.

"An extreme space weather storm - a solar superstorm - is a low-probability, high-consequence event that poses severe threats to critical infrastructures of the modern society," said research physicist Ying D. Liu, with the National Space Science Center of the Chinese Academy of Sciences in Beijing.

"The cost of an extreme space weather event, if it hits Earth, could reach trillions of dollars with a potential recovery time of 4-10 years," Liu said. "Therefore, it is paramount to the security and economic interest of the modern society to understand solar superstorms."

Luhmann echoed Liu's sentiments, comparing CME preparedness to earthquake preparedness.

"People keep saying that these are rare natural hazards, but they are happening in the solar system even though we don't always see them," she said. "It's like with earthquakes - it is hard to impress upon people the importance of preparing unless you suffer a magnitude 9 earthquake."

Satellites such as NASA's STEREO project enable scientists to understand solar storms, and data gathered from them may one day enable scientists to accurately predict solar storms.

"Observations of solar superstorms have been extremely lacking and limited, and our current understanding of solar superstorms is very poor," Liu said. "Questions fundamental to solar physics and space weather, such as how extreme events form and evolve and how severe it can be at the Earth, are not addressed because of the extreme lack of observations."