Coronal mass ejections (CME) are large expulsions of plasma and magnetic fields from the Sun’s corona into the heliosphere that have the potential to severely disrupt life on our planet unless humanity takes action to protect vulnerable infrastructure.
CMEs can travel at speeds ranging from less than 250 kilometers per second (km/s) to almost 3000 km/s, ejecting billions of tons of coronal material. They are often associated with solar flares and other solar activity.
CMEs are large expulsions of plasma and magnetic field from the sun’s atmosphere — the corona. Compared to solar flares — bursts of electromagnetic radiation that travel at the speed of light, reaching Earth in just over 8 minutes — CMEs travel at a slower pace but also contain more than light.
They can be observed as loops or bubbles of dense plasma that interact with the solar wind and interplanetary magnetic field (IMF). When a CME enters interplanetary space, it is called an interplanetary coronal mass ejection (ICME). ICMEs are often characterized by twisted magnetic fields and are commonly referred to as magnetic clouds.
If Earth happens to be in the path of a CME, the charged particles can slam into our atmosphere, disrupt satellites in orbit and even cause them to fail, and bathe high-flying airplanes with radiation.
They can disrupt telecommunications and navigation systems because CMEs can cause geomagnetic storms when they reach Earth, which can disrupt public transportation systems, fuel distribution systems, and GPS.
Solar weather remains a constant. The phenomenon includes solar flares and coronal mass ejections, which can affect Earth at any time. Scientists monitor the sun, like they do terrestrial weather, and study these events to try to predict when and where they will occur.
“The energy from a solar flare will interact with the ionosphere — the outermost layer of the atmosphere that’s critical for radio signals,” said C. Alex Young, associate director for science in the heliophysics division at NASA’s Goddard Flight Center. “When those layers change because they’re heated up, that can cause a degradation in high-frequency radio.”
As a solar flare releases more energy, it can create shock waves that accelerate particles away from the sun, causing what is known as a particle storm. These particles can reach Earth almost as fast as solar flares, in less than an hour. With enough energy, a solar flare can project material away from the sun — a coronal mass ejection. Billions of tons of particles spray out from the sun at high speed, potentially reaching Earth in a day or two.
In an 11-year solar cycle, there can be as many as 2,000 solar flares of varying strength. Not all will produce coronal mass ejections, and in the vast expanse of space, fewer of those will hit Earth.
Scientists can build better predictive models by studying sunspots, and continuously monitoring solar activity.
Solar eruptions can also carry very high-energy particles that can cause radiation poisoning to humans and other mammals. This would be dangerous to unshielded astronauts, such as those traveling to the moon or Mars, and large doses could be fatal.
CMEs can occur several times a day when the sun is most active, but only about once every five days during quieter periods. Fast CMEs occur more often near the peak of the 11-year solar cycle and can trigger major disturbances in Earth’s magnetosphere.
A solar storm making an impact 93 million miles away isn’t theoretical. It has happened, sometimes subtly and sometimes dramatically. Solar flares occur frequently, but usually not with enough force to harm Earth.
Scientists can identify three storms in the past 150 years of sufficient magnitude to cause real disruption: one in 1859, one in 1872 and one in 1921. The first of these, widely referred to as the Carrington Event, sent telegraph machines on the fritz worldwide.
Some of them sparked; some stopped working; others even sent bizarre messages, unprompted by any human. The Carrington Event was the strongest geomagnetic storm on record but we have more technology infrastructure that such a rogue electrical input could influence.
Nowadays, there’s much more to worry about. Nearly everything the modern world relies on could fail if disabled by a serious enough solar storm.
Phenomena like large solar flares and CMEs are most common during periods of “solar maximum” that occur approximately every 11 years — next up around 2025.
The good news is, that researchers estimate that storms of sufficient magnitude to cause real havoc occur only once every hundred or so years.
The bad news is, we’re probably overdue.
A catastrophic solar storm is a “low-frequency, high-consequence” event, which means it’s urgent but rare so we should not be distracted by the smaller disasters the planet suffers more regularly.
Fortunately, governments are paying attention.
The United States Geological Survey has observatories monitoring the planet’s magnetic field. Recently, in collaboration with the National Oceanic and Atmospheric Administration, it has been providing real-time maps to utility companies so they can make smart decisions during a storm about where, if necessary, to modulate or cut the flow of power.
NOAA and NASA also operate satellites 1 million miles from Earth to monitor the sun — and NOAA’s Deep Space Climate Observatory can alert authorities as much as an hour before a CME that’s likely to affect the grid arrives.
The Foundation for Resilient Societies is urging state and local governments to provide protection from electromagnetic pulse, which results from the detonation of nuclear weapons in the upper atmosphere, and geomagnetic disturbance, a related natural phenomenon caused by the ejection of charged particles from the sun impacting the earth’s magnetic field.
Long-term and widespread blackouts are a bigger threat than some people realize. While some officials haven’t emphasized the risks, we can avoid the worst outcomes with the right preparation.