We all know that major storms can wreak havoc, flooding cities and decimating infrastructure. But there’s an even bigger worry than wind and rain: space weather. If a massive solar storm hit us, our technology would be wiped out. The entire planet could go dark.

“We’re much more reliant on technology these days that is vulnerable to space weather than we were in the past,” Thomas Berger, director of the Space Weather Prediction Center at the National Oceanic and Atmospheric Administration told Gizmodo. “If we were hit by an extreme event today, it’d be very difficult to respond.”

“Solar storm” is a generic term used to describe a bunch of stuff the Sun hurls our way, including x-rays, charged particles, and magnetized plasma. A massive solar storm hasn’t hit the Earth since the mid-19th century, but space weather scientists are very worried about the possibility of another.

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Solar Flares

A solar storm usually starts with a solar flare — a giant explosion on the surface of the sun that sends energy and particles streaming off into space. Small, C-class flares occur all the time and are too weak to affect the Earth, while mid-sized M-class flares can produce minor radio disruptions. X-class flares, meanwhile, are the largest explosions in the solar system, releasing up to a billion hydrogen bombs worth of energy. These eruptions occur very rarely, but when they do, they’re an epic sight.

One of the most powerful flares measured with modern instruments took place during a solar maximum in 2003. It was so large it maxed out our satellite sensors, which registered an X-28 (28 types larger than an X-1 flare, which itself is 10 times greater than an M1 flare). Here’s what that event looked like:

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The Solar and Heliospheric Observatory (SOHO) spacecraft captured this epic solar flare in 2003. Image credit: ESA / NASA - SOHO

Despite observing flares for over a century, scientists still aren’t totally sure what causes the Sun to erupt. We do know that flares have a lot to do with disruptions in the Sun’s powerful magnetic field, which oscillates over the course of an 11-ish year solar cycle.

“Solar storms originate in magnetic features that erupt from the surface of the sun,” explained space weather scientist Joe Gurman, speaking to Gizmodo from NASA’s Goddard Spaceflight Center. “We call these active regions, or sunspots. When they’re big and ugly, that’s an indication that the magnetic field is changing rapidly. And when the magnetic field changes rapidly, that appears to be the cause — or related to the cause — of solar activity.”

A mid- to large-sized solar flare would send waves of high energy radiation — x rays and ultraviolet light — zipping toward the Earth. These types of radiation are powerful enough to rip electrons off of atoms. That’s exactly what they start doing when they hit the upper portion of our atmosphere, known as the ionosphere. Basically, the sky gets zapped with a giant electromagnetic pulse. But according to Berger, even the biggest flares don’t impact humans very much.

“It’s a huge EM pulse that roils up the ionosphere, causing it to expand out,” Berger said. “But the solar flare really doesn’t damage technology.”

The one exception is radio. Radio signals between the Earth and orbiting satellites can be blocked when the atmosphere becomes too charged.

“Radio communications are sometimes impacted,” Berger noted. “Over the horizon radio becomes difficult. When airplanes are flying over the poles, the only way they communicate with control centers is high frequency radio waves bouncing over the continents. But it’s just a temporary difficulty lasting ten minutes to hours at the most.”

An X-class flare captured by NASA on March 6th, 2012. Image Credit: NASA Goddard Spaceflight Center / Flickr

We don’t have a great way of forecasting solar flares, and they hit the Earth too quickly for NOAA to provide airline companies with advance notice (it takes about eight minutes for sunlight to reach us).

“The only thing we can do is issue an alert when we see one,” Berger said. “Airlines are very interested in flare effects on high frequency communications, and if there’s a really large event, they’ll consider grounding flights.”

If you’re not an airline operator, you pretty much get to sit this one out. But don’t forget to check out the amazing images over at NASA’s Solar Dynamics Observatory every now and then.

Charged Particles

Minutes to hours after a solar flare lights up the sky, a stream of charged particles — electrons and protons — arrive at the Earth. They bombard the magnetosphere, a protective envelope around Earth created by our magnetic field. “We see the radiation level go up sometimes, which can indicate that particles are impinging on Earth’s orbit,” said Berger.

Charged particles falling into Earth’s atmosphere contribute to the northern lights. Image Credit: Adam Woodworth

Occasionally, a large pulse of charged particles will hit orbiting satellites and damage their electronics. Particle radiation is also a big health risk for humans in space.

“We do have to worry about energetic particles on the ISS,” Gurman said. “If we ever get to the point of being a spacefaring race, they’re going to become a much bigger concern.”

But by and large, the effects of solar particle radiation are buffered by the magnetosphere and atmosphere. It’s what’s coming next that you and me on the ground need to worry about.

Coronal Mass Ejections

When the Sun flares up, it sometimes shoots a giant cloud of magnetized plasma off into space. This is called a coronal mass ejection (CME). CMEs are the slowest form of solar weather, taking anywhere from 12 hours to several days to reach the Earth. They’re also by far the most dangerous.

Fortunately, because CMEs are slow moving, our space weather forecasters have a little more time to anticipate them. They examine images of the Sun, pulled from the SOHO and STEREO satellites. When our observatories see something big, NOAA responds.

Berger outlined what happens next: “A watch is issued when we see something happen on the Sun headed toward the Earth. Typically if there’s a large CME, something major we think could impact the Earth, we put out a watch.”

A CME will shoot pretty much straight out from the Sun, and there’s always a good chance that the Earth won’t end up in its path. If a CME is coming straight at us, it’ll first hit NASA’s ACE satellite, located at the L1 Lagrange point roughly a million miles in front of the Earth. If that happens, we’ve got anywhere from 30 minutes to an hour before a cloud of plasma rains down from above, interacting with our planet’s magnetosphere and triggering a geomagnetic storm.

That’s when you start to see effects on the power grid.

Artist’s depiction of the solar wind colliding with Earth’s magnetosphere. Image Credit: NASA / Wikimedia

“This generates huge electrical currents in upper atmosphere of Earth,” Berger said. “Depending on how conductive the ground is, you can get large currents getting picked up by power stations and fed into the grid.” And that’s bad news, because “our grid isn’t designed for huge amounts of current coming out of the ground.”

Geomagnetic storm strength is measured in “disturbance storm time” or Dst, which essentially describes how hard a CME shakes up Earth’s magnetic field. Ordinary storms, which cause the northern lights to flare up but otherwise don’t impact us, register somewhere in the neighborhood of Dst = -50 nT (nanoTesla). The worst geomagnetic storm of the space age, which knocked out power across Quebec in March of 1989, registered a Dst = -600 nT.

But even that 1989 storm looks puny in comparison to the Carrington event, a geomagnetic storm that zapped the Earth 156 years ago. At the time, the damage wasn’t too bad. But a Carrington-sized storm today could spell disaster.

Monster Storms

The Carrington event of September, 1859 is named for Richard Carrington, the English astronomer who saw the sun flare up with his own eyes. In the days following Carrington’s observation, a series of powerful CMEs hit the Earth head-on, igniting the northern lights as far south as Cuba. Currents electrified telegraph lines, shocked technicians, set telegraph papers on fire, and caused widespread communications outages.

Modern estimates for the strength of this storm range from Dst = -800 nT to -1750 nT.

Things stand to get really dark up in here the next time a Carrington-sized storm hits. Image Credit: NASA Earth Observatory

Human society is far more reliant on electricity today than it was 156 years ago. Berger pointed out that today we have pipelines, electrical transmission grids, and a lot more ground-based electrical conduction technology. So, what would happen if a Carrington-sized event struck us now? Pretty much ever aspect of the modern world would take a hit, according to a report by the National Academies of Sciences.

The ground currents induced by large geomagnetic storms can melt the copper windings of transformers that lie at the heart of power distribution systems. If this happens, it can lead to massive power outages. And because our power grid has grown much more interconnected over time, the effects of such an outage today could be spread far and wide.

A map showing the at-risk transformer capacity by state for a 4800 nT/min geomagnetic field disturbance. Regions with high percentages of at-risk capacity could experience long-duration outages extending for several years. Image Credit: J. Keppenman, Metatech Corp

It’s hard to overstate just how much this would uproot our lives. The lights would of course go out, as would the internet, and any device that draws current from the wall. In places with electronically-controlled municipal water supplies — like most modern cities — toilets and sewage treatment systems would stop working. Heating and air conditioning would fail. Perishable food and medication would be lost. ATMs would be useless. Gas pumps would go offline. And so forth.

GPS technology would also be knocked out. Said Grunman, “The GPS system depends on the very precise timing of a course of signals between two points, like a spacecraft and your phone. If you dump a bunch of energetic particles into the atmosphere, that effects your GPS. Which is sobering when you consider the replacement of old aircraft landing technology with GPS.”

Some of these effects could last years, and they’d be felt globally. “The entire magnetic field of the Earth is changing, so the entire Earth feels it,” said Berger.

Image Credit: Shutterstock

It’s hard to fathom the social consequences of billions of power-hungry humans suddenly being pulled off the grid, but I think we can all agree it wouldn’t be pretty. What we do know for sure is that the economic toll would be enormous. The National Academies report estimates that total cost of a Carrington-sized event today could exceed $2 trillion dollars — 20 times greater than the cost of Hurricane Katrina.

It’s important to keep in mind that we aren’t talking about some incredibly far-fetched, Armageddon-style apocalypse situation here. In fact, in July of 2012, a massive CME ripped through Earth’s orbit and narrowly missed us. That event, which was picked up by NASA’s STEREO-A satellite, would have registered a Dst of -1200 nT — comparable to the Carrington event.

“If it had hit, we would still be picking up the pieces,” space weather scientist Daniel Baker of the University of Colorado told NASA in 2014. “How many other [storms] of this scale have just happened to miss Earth and our space detection systems? This is a pressing question that needs answers.”

Are We Dead in the Water?

Hopefully we can enact some smart mitigation policies before the techno-pocalypse befalls us. Image Credit: Shutterstock

Thanks to a growing army of space weather observatories, we’re much better able to predict CMEs than we were 20 years ago. Still, most space weather scientists agree that if a massive solar storm struck today, we’d be pretty screwed. But we’re trying to change that.

The White House Office of Science and Technology Policy has assembled a task force to explore ways of responding to extreme events. Berger said that they have a national space weather strategy due out in October. The strategy will outlines what the US needs to do to be “better prepared.”

Berger couldn’t comment on the specifics of the policy strategy, so we’ll have to check in again this fall. He did hint that it would be heavy on the recommendations for power suppliers. (Currently, power companies respond to large solar storm warnings by re-routing power distribution around transformers.)

In the meanwhile, what can a space weather-conscious Earthling do? Most of the usual disaster preparedness advice applies. Build an emergency supply kit. Have a plan for getting in touch with loved ones should the phones fail. Keep your car tank at least half full of gasoline. Keep extra batteries on hand, or purchase a solar or hand-crank charger. Back up your data. Make sure you’ve got plenty of spare crowbars — wait, no, that’s the zombie apocalypse.

And of course, you can keep up with the latest solar storm warnings over at NOAA’s Space Weather Prediction Center.

Sources: NOAA Space Weather Prediction Center, NASA Solar Dynamics Observatory, “Solar Flares: What does it take to be X-Class?”, “Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections”, “A massive solar eruptive event in July 2012: Defining extreme space weather scenarios”, “Severe space weather events: Understanding the societal and economic impacts”


Contact the author at maddie.stone@gizmodo.com or follow her on Twitter.

Top image: NASA Goddard Spaceflight Center /Flickr