The Other Corona

There is another event with "corona" in its name that may cause a lot of disruptions on earth. The sun's Coronal Mass Ejections (CME) has a high likelihood of disrupting our electronic way of life for months.

I have been thinking about CMEs since the Texas cold snap (opens new window). While these two are very unrelated things, they have had at least one thing in common: "the chance of electrical grid collapse". This is something we have not experienced as a modern society. CME came up in a conversation recently, so I thought to make put whatever I have learned here.

NOTE: I am pretty much pretending I understand these subjects. I am not academically educated in electrical engineering, nor I am an astrologist. If there is something I am getting wrong, please let me know.

If you don't know what CME is the above video is a nice watch. To summarize it, the sun casts a constant stream of Solar Wind and the earth is like a pebble inside this stream. The planet's magnetic field protects the earth from the effects. Every once in a while, the sun ejects a mass of plasma. If the earth happens to be on the way of that projectile, it will seriously interfere with the earth's magnetic field.

The last time we had a serious one was in the 1800s, and we dodged one in 2012 by just one week! The chance of the next one hitting us is over 1% a year. That's ridiculously high!

# The Trouble

So I wanted to know what happens if we experience a CME event. Will it destroy our personal devices? or the gird? is it gonna interfere with magnetic devices?

And I got the answer everyone hates to hear: it depends.

A CME is not going to boil the surface of the earth, so that's good news. People a few hundred years ago would not have experienced any disruptions in their lives. For the modern world however, it will create two issues:

  1. A temporary and powerful magenitc field which will be felt on the surface of the earth.
  2. This new magentic field is going to be very volatile, inducing electricity in wires.

The issue #1 may be much less of a concern, but 2 can be pretty serious.

# Geomagnetic Storm

Let's start with #1: we already have a magnetic field present on the surface of the earth. Thankfully, it protects us from the solar winds and makes our compasses work. Meanwhile, you are instructed to not bring magnets close to certain electronic devices. For example pacemakers.

Strong magnetic fields would have been a much bigger issue in 2012 than they are today. They can affect CRT monitors and magnetic data storage tapes. If the magnetic filed is strong enough it may interfere with the operation of your phone's microphones, speakers, and compass. Initially, I was worried that it may wipe HDD hard drives but that does not seem to be an issue. I am still not sure if it will interfere with their operation tough.

We have a few historical accounts of CME events, which are somewhat reliable. These come from the Quebec power outage, the storm involving Ottawa, and a storm in 1920s. The Carrington Event though, does not have many reliable records. So there have been estimates of its magnitude based on more recent data. This blog provides an good analysis of the available literature. (opens new window)

The higher margin of these estimates puts the Carrington event at -850nT. For context, the recommended magnetic field levels around cardiac pacemakers is 500 μT (opens new window). So this will be a problem.

I was initially concerned about magentic data storage, but it turns out that Hard Drives are pretty resilient to external magnetic fields. That said, data centers may shut down during the CME event, not necessarily for the fear of data loss, but because of the errors the CME may produce in the operation of the drives. Other archival forms of magnetic films/disks may be affected too.

# Induced Electricity

Now on to issue #2.

The most common way to make electricity is passing a magnet through a wire winding. This is the basis of harvesting electricity from all common sources with the exception of solar. The simple presence of the magnetic field is not enough, it is the change of the magnetic field that matters. As the CME's megnetic field takes hold, fluctuates, and goes down, the events will create electricity in wires.

Around the sun's corona, the power of these fields can be around 4000 volts per meter (opens new window). Ouch.

Luckily, we will be getting extremely smaller numbers on the surface. Moreover, the electricity flows per the right-hand rule. The wires must be in the same orientation compared to the magnetic field. If the wire turns, the effect causes opposite directions of electron flow in different parts of the conductor, canceling the effect.

So there remains one prime candidate for the effect: the electricity gird. Long conductive wires going in one direction. Other infrastructure such as underground metal pipes and railways (opens new window) are susceptible too.

I will talk about the grid separately because there are some other info to expand on. It is a pretty serious issue. Lots of complications can cause a prolonged black out for everyone, even if you are equipped with a solar panel.

Let's just focus on the household electronics for now. Assuming that all electronic components can handle 3 volts, the estimate from the Carrigton event is way too small to directly matter at the household scale.

For CME to matter, it needs to be at least tens of times bigger. That is, the magnetic field must be much stronger or the fluctuations need to happen much more violently.

If we ever face something like that, there are ways to prepare.

# During The Event

The US has a "Space Weather" observer that will give warnings (opens new window) about the CME. The heads-up time we have for the warning varies. We need a few days (opens new window) to accurately assess the danger, but the fastest storms can reach us in under a day.

The mangitute of the impact is defined by K-index and NOAA Scale (opens new window). The largest scale is K=9 and G5 the Carrington event's upper estimate exceeds both of these in terms of scale. So the scale may not say how bad the CME is beyond some point.

The impact can happen in a number of ways depending on the angle of the shape of the incoming magnetic field.

The CME's magnetic field can disrupt, or align with our field.

Picture holding two bar magnets in your hands. If you orient them the same way, you can't easily get them to touch each other because the poles are the same. As you rotate one of them, this repelling force fades away. Beyond 90 degrees of angle difference, turns into attraction.

This will be the case for CME too. It can depart the surface of the sun at any angle. So when it hits the earth, it can fight our magnetic field or merge into it.

I am not quite clear how much difference this would make in the magnitude of what's felt on the surface, but it seems to make a difference for when it is felt. If the polarity of the storm is aligned with the earth's, the CME will cause a head-on interference. If the polarities are opposite, the CME will merge with the earth's magnetic field, but the excess magnetic energy eventually "snaps" (opens new window).

This snapping can accelerate charged particles to an extreme level. In fact, very recently a new electric rocket engine was proposed based on the same concept because it is a very affective way of turning energy into the motion. In the case of a CME however, that means a shorter and stronger magnetic wave.

# Preparation

I am not convinced that we will ever see anything so catastrophic that would require the following preparations. In the meantime, we have very little historical context for these events. A primitive society would not have been negatively impacted by such event. We are the very first generations of societies with vulnerability to such events. So it wouldn't hurt knowing about shielding against such events.

A metal box (opens new window) reduces the reach of the magnetic field inside it. So in a very serious event, putting the valuable electronics adds protection. The protection depends on the metal box thickness (opens new window)

Effect of magnetic field on a metal plate

The electronics inside need a buffer with the metal box itself. That's because the magnetic field still extends to a certain extent inside the box and also the box may pick up charge and the pointy edges can cause sparks. Although if that ever happens, looks like we will have bigger problems. I picture it the way we see in movies, electric arcs and zapping sounds all around the room.

I looked around my home for metal boxes, the dryer and the dishwasher appear to be the places with the least gap in the metal parts. Microwaves by design are great cages for the electromagnetic wave they produce, but they are not better than a metal box overall.

Foregoing the fringe possibilities explored above, the risk to the grid is a much more important topic. I have discussed that in a dedicated post.