They tend to happen during solar maximum, when there are most sunspots. But the biggest ones can happen at any time.
There's no risk to humans. But there is a risk to the electricity transmission network and to satellites mainly.
Ordinary strong solar flares aren't really a problem, there is enough warning and the electricity companies and so on can take measures to protect themselves. Impacts of Strong Solar Flares. We get those every so often, every decade or so.
But then - there's the possibility of a really big solar flare.
There was a big solar flare back in Solar storm of 1859. Known as the "Carrington event" after an English astronomer who was observing the sun, saw some huge sunspots, and spotted an intense white flash from the sunspot group.
The auroras turned night to day, people could read the newspaper by the auroras. Gold minors in the Rocky Mountains woke up and ate breakfast at 1 a.m. thinking it was sunrise on a cloudy day.
Telegraphs stopped working - and in the USA, some operators disconnected the batteries and found they could send telegrams just using the induced electricity from the storm. See Severe Space Weather Events
Telegraph operators also saw sparks leaping from their equipment, some big enough to cause fires. What If the Biggest Solar Storm on Record Happened Today?
So - at the time that was just a curiosity and hardly made any difference to anyone except the telegraph operators and people woken up early by the bright auroras.
But if we had a storm like that now, the effects could be huge. We have never had a flare anything like that big since then.
It could knock out many of our satellites including GPS. It could destroy the transformers in our electricity grid for transmission of electricity.
And the risk maybe higher than expected. One physicist worked out that the risk is 12% of such an event in the next 10 years. Near Miss: The Solar Superstorm of July 2012
So there's been a fair bit of attention about this. Things like hardening the electricity grid in case we have an event like this.
Basically the power companies need to install monster surge protectors.
Solar Storms: What You Need to Ask Your Power Company
And another approach involving adding extra resistors - this amounted to a total cost of the order of $100, million, for an event that could cost trillions (between 0.6 and 2.4 trillion dollars to replace damaged transformers after sch an event according to the Lloyds report) and mean outages of electricity for between 6 days and years.
An Inexpensive Fix to "Prevent Armageddon"
But Congress didn't pass the bill that was proposed to spend this $100 million on this fix.
I'm not sure of the latest on this.
Amongst all the various things that people worry about that are very unlikely to happen - this is one of the few that hardly anyone is concerned about, but could happen. We don't know much about how often these solar storms happen. The sun is quite hard to predict because we don't have that long a timeline of observations and sometimes it behaves very differently from other times.
Sooner or later surely we will get another Carrington event. Maybe not for another century or more, but it could be sooner. And we are not that well prepared for it. Though there's been some attention to this.
And it's not hugely expensive to protect the grid, if it is just $100 million to protect the States.
Presumably they would ground planes if the astronomers predicted that something like this was imminent and warn people that GPS is likely to be unreliable or stop working during the event. Nowadays we'd get at least a bit of warning of it.
I'm not sure there is much else one can do to prepare for it individually. The long transmission lines like the electricity grid are the ones that are especially vulnerable, and satellites. That's why they got currents passing through the telegraph lines in 1859 - because the lines were so long continuous. It's more something that needs government initiatives.
And again as individuals, if it happened the main effect would be power blackouts. Which given how much we depend on electricity these days, compared with 1859, could be quite a major issue.
You might also get power surges in the electricity grid. So good idea to protect your electronics with surge protectors (if not already to protect from lightning).
There's a lot about this online but it can be a bit hard to sift the accurate sites from the ones that are a bit over the top and sensationalist.
But - think - big power cuts over large parts of the world, which don't get fixed quickly because it's not just a break in the power lines, but transformers are destroyed by the big power surges - and very expensive to fix everything - because you have to replace a lot of expensive equipment in a short period of time - that's the sort of thing that they are mainly concerned about. And some satellites could fail including GPS which might be quite a major thing in our modern world.
Blackouts certainly can happen, this is something that actually did happen in Quebec in 1989
You are most vulnerable in the higher lattitudes so the North of the US would be the ones who lose power, and the higher lattitude countries in Europe. Apparently also more vulnerable if the power lines run above igneous rocks.
And - is something you can do something about - ways of protecting the transformers in power grids seem the most important thing to focus on. I think I remember hearing something about this but can't seem to find it online, recent story about that like in the last year or two. Anyone else got more up to date information on this?
Most of the sources I found here were from about a year or two ago, and it is a field where it's probably important to be bang up to date.
UPDATE:
There's a useful recent discussion here at physicsstackexchange:
Can a Coronal Mass Ejection (CME) cause a blackout on Earth and why?
Where one of the answers says that the power network has various unintended protections built in, mainly that if one transformer blows out, the rest in the grid tend to trip rather than blow out too. And that in a study that he and some colleagues did, they found the power grid may be less vulnerable than previously predicted because of these reasons, but satellites that orbit at geostationary orbit, also the middle level orbit GPS satellites may be more vulnerable than previously expected, with many of them, if on the sun side of the Earth (between it's magnetic field and the sun) likely to be destroyed.
There's no risk to humans. But there is a risk to the electricity transmission network and to satellites mainly.
Ordinary strong solar flares aren't really a problem, there is enough warning and the electricity companies and so on can take measures to protect themselves. Impacts of Strong Solar Flares. We get those every so often, every decade or so.
But then - there's the possibility of a really big solar flare.
There was a big solar flare back in Solar storm of 1859. Known as the "Carrington event" after an English astronomer who was observing the sun, saw some huge sunspots, and spotted an intense white flash from the sunspot group.
The auroras turned night to day, people could read the newspaper by the auroras. Gold minors in the Rocky Mountains woke up and ate breakfast at 1 a.m. thinking it was sunrise on a cloudy day.
Telegraphs stopped working - and in the USA, some operators disconnected the batteries and found they could send telegrams just using the induced electricity from the storm. See Severe Space Weather Events
Telegraph operators also saw sparks leaping from their equipment, some big enough to cause fires. What If the Biggest Solar Storm on Record Happened Today?
So - at the time that was just a curiosity and hardly made any difference to anyone except the telegraph operators and people woken up early by the bright auroras.
But if we had a storm like that now, the effects could be huge. We have never had a flare anything like that big since then.
It could knock out many of our satellites including GPS. It could destroy the transformers in our electricity grid for transmission of electricity.
And the risk maybe higher than expected. One physicist worked out that the risk is 12% of such an event in the next 10 years. Near Miss: The Solar Superstorm of July 2012
So there's been a fair bit of attention about this. Things like hardening the electricity grid in case we have an event like this.
Basically the power companies need to install monster surge protectors.
Solar Storms: What You Need to Ask Your Power Company
And another approach involving adding extra resistors - this amounted to a total cost of the order of $100, million, for an event that could cost trillions (between 0.6 and 2.4 trillion dollars to replace damaged transformers after sch an event according to the Lloyds report) and mean outages of electricity for between 6 days and years.
An Inexpensive Fix to "Prevent Armageddon"
But Congress didn't pass the bill that was proposed to spend this $100 million on this fix.
I'm not sure of the latest on this.
Amongst all the various things that people worry about that are very unlikely to happen - this is one of the few that hardly anyone is concerned about, but could happen. We don't know much about how often these solar storms happen. The sun is quite hard to predict because we don't have that long a timeline of observations and sometimes it behaves very differently from other times.
Sooner or later surely we will get another Carrington event. Maybe not for another century or more, but it could be sooner. And we are not that well prepared for it. Though there's been some attention to this.
And it's not hugely expensive to protect the grid, if it is just $100 million to protect the States.
Presumably they would ground planes if the astronomers predicted that something like this was imminent and warn people that GPS is likely to be unreliable or stop working during the event. Nowadays we'd get at least a bit of warning of it.
I'm not sure there is much else one can do to prepare for it individually. The long transmission lines like the electricity grid are the ones that are especially vulnerable, and satellites. That's why they got currents passing through the telegraph lines in 1859 - because the lines were so long continuous. It's more something that needs government initiatives.
And again as individuals, if it happened the main effect would be power blackouts. Which given how much we depend on electricity these days, compared with 1859, could be quite a major issue.
You might also get power surges in the electricity grid. So good idea to protect your electronics with surge protectors (if not already to protect from lightning).
There's a lot about this online but it can be a bit hard to sift the accurate sites from the ones that are a bit over the top and sensationalist.
But - think - big power cuts over large parts of the world, which don't get fixed quickly because it's not just a break in the power lines, but transformers are destroyed by the big power surges - and very expensive to fix everything - because you have to replace a lot of expensive equipment in a short period of time - that's the sort of thing that they are mainly concerned about. And some satellites could fail including GPS which might be quite a major thing in our modern world.
Blackouts certainly can happen, this is something that actually did happen in Quebec in 1989
You are most vulnerable in the higher lattitudes so the North of the US would be the ones who lose power, and the higher lattitude countries in Europe. Apparently also more vulnerable if the power lines run above igneous rocks.
"Power systems in areas of igneous rock (gray) are the most vulnerable to the effects of intense geomagnetic activity because the high resistance of the igneous rock encourages geomagnetically induced currents (GICs) to flow in the power transmission lines situated above the rock. "
The Day the Sun Brought Darkness
And - is something you can do something about - ways of protecting the transformers in power grids seem the most important thing to focus on. I think I remember hearing something about this but can't seem to find it online, recent story about that like in the last year or two. Anyone else got more up to date information on this?
Most of the sources I found here were from about a year or two ago, and it is a field where it's probably important to be bang up to date.
UPDATE:
There's a useful recent discussion here at physicsstackexchange:
Can a Coronal Mass Ejection (CME) cause a blackout on Earth and why?
Where one of the answers says that the power network has various unintended protections built in, mainly that if one transformer blows out, the rest in the grid tend to trip rather than blow out too. And that in a study that he and some colleagues did, they found the power grid may be less vulnerable than previously predicted because of these reasons, but satellites that orbit at geostationary orbit, also the middle level orbit GPS satellites may be more vulnerable than previously expected, with many of them, if on the sun side of the Earth (between it's magnetic field and the sun) likely to be destroyed.
Any other links on this?
"So the most recent idea is that our satellites are very vulnerable but our power grids may not be as vulnerable as we originally thought (though, all of these issues are incredibly difficult to model and predict so take my comments with a grain of salt)."
- see the conversation here: Can a Coronal Mass Ejection (CME) cause a blackout on Earth and why?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.4k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0