The Earth Was Lucky to Dodge a Massive Solar Magnetic Storm in 2012


This image combines data from two coronagraphs and an extreme ultra-violet imager (green) on STEREO A. The CME is the bright streaks emanating from the sun. A coronagraph is a telescope that uses a disk to block the sun's bright surface revealing the solar corona.

When the largest magnetic storm ever recorded struck Earth in 1859, telegraph systems failed across North America and Europe and gave electric shocks to some telegraph operators. Researchers recently analyzed a similarly huge magnetic storm that missed Earth by just nine days in 2012, which could have caused trillions of dollars worth of damages to satellites and power grids.

Two nearly simultaneous coronal mass ejections from the sun on 23 July 2012 propelled the magnetic storm through the solar wind to a speed of more than 2 000 kilometers per second—about four times faster than a typical magnetic storm—and released the energy equivalent of a billion hydrogen bombs. Fortunately for Earth, the magnetic cloud ripped through Earth's orbit when our planet was on the other side of the sun. Had it struck Earth, the magnetic storm's impact could have easily rivaled the so-called Carrington Event of 1859 because of our modern-day dependence upon vulnerable electrical systems.

"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 Ying D. Liu, a physicist at the State Key Laboratory of Space Weather at the National Space Science Center in Beijing, China, in a press release. "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."

One study by the Lloyd's insurance market from 2013 estimated the cost of a solar magnetic storm similar to the Carrington Event to have a potential price tag of up to $US 2.6 trillion for North America. A much smaller solar magnetic storm in 1989 led to 15 simultaneous failures in Canada's Hydro-Quebec power grid and a province-wide blackout with the loss of electricity to six million people for up to nine hours.

Liu, formerly a postdoctoral fellow at the University of California, Berkeley, worked with a team of U.S. and European researchers to analyze the 2012 solar outbursts detected by NASA's Solar Terrestrial Observatory (STEREO) A probe. Their work is detailed in the March 18 issue of the journal Nature Communications.

The researchers' analysis suggests the magnetic cloud reached such high speeds because of a previous mass ejection four days earlier that had cleared the path of materials that would have slowed things down. They also found the 2012 outburst produced an long-lasting, southward-oriented magnetic field that tends to drive the largest magnetic storms when they hit Earth. Such a southward-oriented field can merge with Earth's northward field and allow the magnetic storm to channel energy directly into the Earth's poles.

"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," said Janet G. Luhmann, a physicist at the University of California, Berkeley.

Today's solar magnetic storm forecasts offer just 30 to 45 minutes of lead time for power grid operators and others to prepare. But new spacecraft such as NASA's Deep Space Climate Observatory, scheduled for launch in 2015, could offer improved observation and understanding of the sun that leads to forecasts with longer lead times. Researchers could also refine their rating of solar storms to give power grid operators a better understanding of whether a particular storm could have a severe impact on their electrical equipment.


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