March 20, 2014
In July 2012, Earth was almost hit by a massive cloud of fast-moving solar material, named coronal mass ejection (CME), that could have had costly consequences had it hit our planet.
Coronal mass ejection that left the Sun on July 23, 2012. Credit: NASA/STEREO
Coronal mass ejection (CME) is a pulse of charged plasma released into space by the Sun. Almost two years ago, two CMEs preceded by another path-clearing CME nearly missed the Earth. Had it hit our planet, consequences would have been enormous, one might even call them catastrophic.
This solar superstorm was moving at 2900 km/s and had it occured nine days earlier we would have been in its way, satellites in Earth's orbit would have been disabled, power utility grids would have suffered electric surges and communication systems would have been taken down.
The storm was detected by NASA's two STEREO (Solar Terrestrial Relations Observatory) spacecrafts and the following research by a team of international scientists was published Tuesday in Nature Communications.
"The authors believe this extreme event was due to the interaction of two CMEs separated by only 10 to 15 minutes," said Joe Gurman, project scientist for STEREO at NASA's Goddard Space Flight Center in Greenbelt, USA. He did not take part in the research paper. "Plus the CMEs traveled through a region of space that had been cleared out by another CME four days earlier."
The coronal mass ejection that had erupted four days prior to the main event had swept aside particles along the path and affected Sun's magnetic fields, both of which had made it easier for two CMEs that followed to erupt, making them move faster through space. At the time, Earth was luckily on the other side of the Sun.
"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 paper co-author Ying D Liu, National Space Science Center of the Chinese Academy of Sciences in Beijing, China. "The cost of an extreme space weather event, if it hits Earth, could reach trillions of dollars with a potential recovery time of four to 10 years. Therefore, it is paramount to the security and economic interest of the modern society to understand solar superstorms."
Earth's magnetic field protects us against solar winds, but a magnetic storm travelling 2900 km/h is a couple of times faster than a normal magnetic storm and it had energy equal to a billion hydrogen bombs. We don't have ways to defend against CMEs of this magnitude, but early warning system could help us be prepared in other ways. However, we first have to understand these storms better.
"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," said Janet G. Luhmann, one of the research leaders. "It's like with earthquakes – it is hard to impress upon people the importance of preparing unless you suffer a magnitude nine earthquake."