What happens when a Coronal Mass Ejection hits the Earth?

At approximately 11:00 am Eastern time (15 minutes from now as I type this), the Earth will come into contact with the largest Coronal Mass Ejection since 2005—a huge burst of charged particles and magnetic fields that exploded off the surface of the sun Sunday night.

Scientists have been tracking it as it headed our way. In fact, intrepid astronomy reporter Lee Billings contacted me this morning to tell me that ejection had just passed our Advanced Composition Explorer satellite, which is why we have such a precise estimate of when it would hit Earth. Despite the size of this CME, Billings says it probably won't cause any major damage. However, a larger CME that hit us with less warning very well could be a huge problem. That's because CME's can interfere, to varying degrees, with radio communications, GPS signals, and lots of other electronic stuff that we've come to rely on. What's more, Billings says, our warning system is aging fast. That ACE satellite, for instance, has enough fuel to survive to 2024, but it's equipment is old enough that it's likely to fail at any time.

Lee has written a great piece on Coronal Mass Ejections and the very real risks they pose to modern technology over at Popular Mechanics. It's a great breakdown of what CME's can do and what we do to prepare for them that manages to get the risks right, without becoming too hyperbolic and apocalyptic-y. It's 10:59 AM now. Happy CME!

A geomagnetic storm produces dangerous electrical currents in a manner analogous to a moving bar magnet raising currents in a coil of wire. When a CME hits the Earth’s magnetic field and sends it oscillating, those undulating magnetic fields raise currents in conductive material within and on the Earth itself. The currents that ripple through our planet can easily enter transformers that serve as nodes in regional, national, and global power grids. They can also seep into and corrode the steel in lengthy stretches of oil and gas pipeline.

On October 29, 2003, power grids around the world felt the strain from the geomagnetic currents. In North America, utility companies scaled back electricity generation to protect the grid. In Sweden, a fraction of a CME-induced electric current overloaded a high-voltage transformer, and blacked out the city of Malmo for almost an hour. The CME dumped an even larger mass of energetic particles into Earth’s upper atmosphere and orbital environment, where satellites began to fail because of cascading electronics glitches and anomalies. Most were recovered, but not all. Astronauts in low-Earth orbit inside the International Space Station retreated to the Station’s shielded core to wait out the space-weather storm. Even there, the astronauts received elevated doses of radiation, and occasionally saw brief flashes of brilliant white and blue—bursts of secondary radiation caused when a stray particle passed directly through the vitreous humor of the astronauts’ eyes at nearly light-speed.

Flares and CMEs from the Sun continued to bombard the Earth until early November of that year, when at last our star’s most active surface regions rotated out of alignment with our planet. No lives were lost, but many hundreds of millions of dollars in damages had been sustained.

The event, now known as the Halloween Storm of 2003, deeply worried John Kappenman, an engineer and expert in geomagnetic storm effects. The Sun had fired a clear warning shot. Its activity roughly follows an 11-year cycle, and severe space weather tends to cluster around each cycle’s peak. The Sun’s next activity peak is expected to occur this year or next, and the chance of more disruptive geomagnetic storms will consequently increase

The video above shows what the last big CME, in 2005, looked like. Video Link