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These “solar storms” are incredibly powerful and can be extremely destructive to life on our planet – to put it mildly. Fortunately, Earth has some defenses.
Brewing solar storms
Solar storms generally occur because of variations in the Sun’s magnetic field lines. Disturbances in the Sun’s magnetic field well up to the solar surface and appear as dark, planet-sized regions called “sunspots.” The powerful magnetic fields around sunspots inhibit convection, which ultimately makes these regions appear cooler and darker, and generate active regions on the Sun.
When the Sun’s magnetic field lines fluctuate and realign into a less tense configuration, a process called magnetic reconnection, the result is a gigantic explosion of energy. We call these events “solar storms,” and they may take the form of a solar flare or a coronal mass ejection (CME), both of which are specific kinds of solar storms.
A solar flare is a very intense, localized explosion that unleashes tremendous amounts of energy. This high-energy radiation races through the solar system at the speed of light. As the solar flare careens across the cosmos, it sweeps up protons and accelerates them into a high-speed proton storm. Eight minutes and 20 seconds later, we look up and see the Aurora – Earth’s atmosphere protecting us by absorbing this energy high in the atmosphere.
And we desperately need this protection, as the most extreme solar flares, called X-class solar flares, can release as much energy as one billion hydrogen bombs.
Admittedly, it’s a bit difficult to grasp how much one billion is. Hopefully, the image below gives you the context you need to imagine the magnitude we’re talking about here. The little tiny dot underneath the "1" is the amount of energy released in one hydrogen bomb. The huge block to the right shows you how many little tiny dots it takes to make one billion.
If that didn’t help you understand just how big the number one billion is, let’s take another stab at this.
While a solar flare is a bright flash of light emanating from the Sun, a CME is an enormous cloud of solar matter hurled into space, sometimes toward Earth (eep!).
In short, CMEs are massive eruptions. They cause huge clouds of magnetized particles to burst forth from the Sun, much like a cannonball. CMEs contain millions or even billions of tons of plasma, and they shoot through the solar system at speeds reaching 5.6 million mph (9 million km/h). This pace is much slower than a solar storm, but it’s still fast enough to give us little time to react. They can reach our planet in as little as 15 hours.
As the electrified plasma moves toward us, it’s deflected by the Earth’s magnetic field and diverted to the North and South Poles. As energetic particles fall into the atmosphere, the atmosphere glows, and we look up to see the beautiful auroras we know and love.
But, of course, our atmosphere isn’t impenetrable, and not everything about a CME is so wondrous and beautiful.
How could CMEs impact Earth?
On September 18, 1859, a chunk of the Sun slammed into Earth in a particularly bad solar storm known as “the Carrington Event.” Telegraph operators were electrocuted, wires snapped and caught fire, and auroras occurred around the globe — they were seen in Colorado and as far south as Hawaii and Cuba. The auroras were so bright that people could use their light to read their newspapers.
It was one of the strongest solar storms ever recorded, and scientists believe it was a CME.
If a CME of a similar magnitude occurred today, it could be even more catastrophic. Nowadays, a solar storm like this could lead to satellite malfunctions and create additional drag on objects in low Earth orbit, causing them to slow and potentially plummet into our planet. And as a friendly reminder, the International Space Station is in low Earth orbit.
Passengers on commercial jets flying over polar regions could be exposed to increased electromagnetic radiation, which could pose some health risks.
And that’s just the start of our troubles. Power grids are more vulnerable now than ever, as almost all of our infrastructure and services depend on electric power. Sprawling power lines that allow long-distance transmission of relatively low-cost power make economic sense, but they would act like antennas, picking up the currents and spreading the problem over wide areas, causing a massive cascading failure.
The loss of electricity would have a ripple effect across social infrastructure. Water distribution would be affected in hours, and perishable foods and many medications would be lost within a day. And if the CME is of a high enough magnitude, the blackouts could last for days or even weeks.
The social and economic disruptions would be extremely extensive. A study by the National Academy of Sciences concluded that a repeat of the Carrington Event today could cause $2 trillion in damage, affecting telecommunications, banking and finance, and transportation, just to name a few.
How could CMEs affect astronauts?
On top of this, anyone not protected by the Earth’s life-giving magnetic field could be severely harmed. We got a taste of the scale of this on January 20, 2005, when a giant sunspot exploded and hurled a billion-ton cloud of electrified gas (or CME) into space. It was a days-long proton storm, with high-speed protons packing more than 100 million electron volts of energy.
What would have happened if our astronauts were in the path that day?
Unfortunately, it wouldn’t have gone well. Spacesuits offer little protection, and the astronauts would have absorbed about 50 rem of ionizing radiation. That is enough to give them radiation sickness, which would mean vomiting, fatigue, and low blood counts for days. Although this certainly doesn’t mean death, the situation is made more grave by the lack of medical care in space and the difficulties associated with quickly returning to Earth.
Of course, we would have some warning. After all, instruments worldwide (and in space) monitor the Sun every second of every day. So, let’s say we are fortunate. We detect things nearly as soon as they start brewing. Exactly how long do we have to prepare?
At best, we’d have a day to get ready for what’s surging toward us.
How active is the Sun, really?
Every 11 years or so, the Sun’s magnetic field flips, reversing its north and south poles. Solar storms are more likely to occur during the high points of the cycle. So. At this point, you might wonder, where are we now in the cycle? Having passed the solar minimum in December 2019, scientists expect the Sun to ramp up activity as it approaches the predicted maximum in July 2025.
Thankfully, even during these peak periods, catastrophic solar events are rare, so we don’t really need to live in terror of an impending techno-apocalypse. After all, Carrington-level events only occur at an average rate of once every 500 years.
But we do need to take the threat seriously and start making the necessary upgrades. As far smaller storms have wreaked havoc on Earth, and without proper preparation, it will happen again. Case in point: In March of 1989, a solar storm three times smaller than the Carrington Event caused the Hydro-Quebec electrical grid to collapse. The blackout lasted nine hours, leaving more than 5 million people in the dark.
Fortunately, scientists are working hard to improve how we predict the strength and duration of solar cycles in order to be able to forecast solar storms more effectively. But it's not an easy feat because our Sun is so variable. It can take months after the start of a new cycle to be able to spot (pun intended) sunspots and track the solar cycle’s progress.
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