So the background is simple: in the modern day a CME (coronal mass ejection, a solar flare that has escaped the sun) hits the Earth and destroyed all the electrical equipment causing planes to crash and roads to instantly be filled with wrecks, power plants to became useless and power grids destroyed.

My question is simply how big does a CME need to be to make that happen? Would other equipment be destroyed by such an electromagnetic flare? What other secondary effects would this CME have?


In light of previous comments and answers I am changing this question to fit my increased knowledge of this subject. So what I am wanting to know is how big of a coronal mass ejection would be needed to destroy the modern electrical grid and cause most of our transport infrastructure to fail. I only want modern civilization to break down with this flare, some electronic equipment can still work after the ejection because of this. I am simply wanting it to cause a big enough immediate disaster and technological regress to where society would enter a dark age and take many generations to come back to a modern world. so how big of a coronal mass ejection would I need?

  • $\begingroup$ One that will annihilate life on earth! It should be a 24-hour lasting flare wrapping the world pole-to-pole. Have you seen the end of the movie "Knowing"? $\endgroup$ Jun 30, 2018 at 16:48
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    $\begingroup$ Some heavy electrical equipment is designed for very high voltages or amperages - those won't be be 'destroyed' without a real world-ender. Are you sure you want your threshold to be ALL electrical equipment? $\endgroup$
    – user535733
    Jun 30, 2018 at 18:13
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    $\begingroup$ No solar flare would destroy all (or even most) electronic equipment without also killing all people. The dangers of solar flares are related to the induction of large currents in big devices, such as power distribution cables. The phone in a person's pocket is too small to be affected by an EMP which wouldn't also induce a large current in the person. After all, a human is a 1.5 to 2 meters long electrical conductor. $\endgroup$
    – AlexP
    Jun 30, 2018 at 19:57
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    $\begingroup$ Since you are asking for hard science, it might be appropriate for you to demonstrate in your question that you understand the issue in principal. Otherwise, well, who is going to put a lot of effort into writing an answer that you end up not understanding? Where does one even start to answer this question? $\endgroup$
    – Raditz_35
    Jun 30, 2018 at 20:37
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    $\begingroup$ What you asking is a called "mass coronal ejection'. Please note a mass coronal ejection on the scale you propose will take about six days to travel from the Sun to the Earth. This is enough time for the human race to respond by turning off all their electronic devices and electrical technology until the moment of disaster passes. $\endgroup$
    – a4android
    Jul 1, 2018 at 1:45

2 Answers 2


You're not looking at a solar flare, but rather a massively acute coronal mass ejection.

Solar flares happen all the time and while they can cause temporary disruption to delicate communication technologies all the way up to power grids depending on the size of the solar flare, they very rarely cause 'permanent' damage. Solar flares can cause a massive amount of disruption to the flow of electricity through an electronic circuit, but it's not common for them to damage electrical circuits directly.

We actually have solar flares hit us all the time and we even have an 11 year cycle of solar maxima that regularly hit the earth and have brought down power grids in the past without destroying infrastructure. Solar flares simply aren't powerful enough to do that kind of damage without being a sustained effect over a significant period.

Coronal Mass Ejections on the other hand (see original link) is more or less a massive plasma blast shot from the sun into space, potentially at the Earth. This will do much more damage, but even then you're dealing with a massive one to actually destroy electrical systems. More to the point, if it can do that, there is a small risk to humans, especially at high altitude.

As for the actual impact of a CME; You're dealing with between 2 and 5 days of ejecta, reaching between 20 and 3200 Km/s speeds, and you're dealing with around 1.6×10^12 kg worth of plasma mass. These generally cause issues with Earth's infrastructure, but doesn't wipe it out completely. That is (in part) because a 5 day ejection window means it's pretty hard to hit a moving target like the Earth with the full mass of the CME.

To wipe out all electronics, I'm going to estimate a CME mass of around 10 times the average CME mass, so 1.6 x 10^13 Kg, released in around 5 hrs. That means a CME of around 240 times the normal release load (at least for the 5 hr window we describe). If all that hit the Earth, we'd be in trouble. You'd probably know it was happening because you'd see aurorae as far north as Brisbane Australia (Aurora Australis), and as far south as Los Angeles (Aurora Borealis) just because of the sheer mass of material reacting with the Earth's magnetic field. It's also likely at that magnitude to do at least some damage to life forms even on the surface of the Earth.

It should be pointed out that such a massive CME is highly unlikely because the Sun would have yielded to the causative pressures long before that kind of pressure could build up. Given our current theories on how CMEs form and are released, this kind of scale is likely impossible.

In any event, if you're in the tropics and you're seeing aurorae, turn off as much of your electrical equipment as you can and stock up on sunscreen and anti-plasma burn first aid kits (the first one is a joke by the way; sunscreen wouldn't help you much).

  • $\begingroup$ How much of the night side of the earth would be shielded (by the earth) from these effects? $\endgroup$
    – Jasper
    Jul 1, 2018 at 5:08
  • $\begingroup$ @Jasper probably a lot; that's something I didn't factor in. But, let's say that you can get a targeted release of material focused on where the earth is going to be over a 12 hr period, then you could wipe it all out, pretty much. That said, even a 6 hr window will give you up to 75% of the earth's surface. If that surface area was (say) the Pacific Ocean, 6 hrs would take out everything except for those places in Russia and Alaska that sit on the edge of the Bering Sea. $\endgroup$
    – Tim B II
    Jul 1, 2018 at 5:16
  • $\begingroup$ so now I just need to know how to narrow the scope of destruction. $\endgroup$
    – skout
    Jul 4, 2018 at 4:52

It will not destroy ALL electrical equipment. Will you settle for a trillion or so dollars?

In 1859 there was a massive solar storm, a coronal mass ejection as noted by Tim B II. As described here, this was powerful enough to cause aurora effects at tropical latitudes and damage the telegraph network that existed at the time - this network was much more resistant to overvoltage damage than most modern equipment. A recent estimate by Lloyds and the AER estimated that if this event were repeated it would cause to the U.S. alone 0.6-2.6 trillion dollars worth of damage.

However, while some telegraph operators experienced electric shocks, there were no serious injuries or deaths reported as a direct result of this event.

Such an event will not destroy all electrical equipment on Earth, because a) only equipment on the side facing the event will be affected (unless the event lasts for a full day) and b) some equipment is either by its nature or deliberately hardened to be resistant to overvoltage effects (see below). Without spending an excessive amount of time determining what is the most resistant equipment on Earth and what level of overvoltage it can survive, the question as asked is not explicitly answerable.

Additionally, any equipment which is sufficiently Faraday shielded by design or happenstance is extremely resistant to damage, for example, any equipment in a submerged vessel, many tunnels, even some underground garages.

Acknowledgement: The majority of this answer was provided by Securiger in conversation and is included with permission.


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