Just 162 years ago – on the morning of September 1, 1859 – an amateur astronomer named Richard Carrington looked through his telescope and noticed “two spots of very bright and white light” in the sky. Outside Carrington’s estate, telegraphs were out of service throughout the world. That night in American cities, people walked, staring up at the sky in surprise: “The northern skies were beautifully lit,” said a reporter for the New York Times.
It was what was later dubbed the Carrington Event: a powerful geomagnetic storm that NASA says is “arguably the greatest and most famous space weather phenomenon of the past two hundred years.” Originating as it did in the rapidly modernizing 19th century, as opposed to the hyper-modernized 21st century, its effects were mercifully limited. We have a lot more electricity these days: another Carrington event could be disastrous.
So are we risking another one? When will Carrington’s next event happen? This week Guise askswe reached out to a number of experts to find out.
Deputy Director of the National Center for Atmospheric Research
A tough question, and, you guessed it, a question without a definitive answer … We could answer it, but it is always a hotly debated subject in the research world.
The correct answer is that they can appear almost any time the sun is producing sunspots. I say this because even within the sunspot cycle there are certain windows when big storms happen, and not always when the sun forms large sunspots – size does not always matter. However, the complexity of these spots matters. The vast majority of violent storms come from what we call “deltoid” regions – those that become terribly entangled when they occur and release this accumulated energy into space in an impressive way in no time!
So, if cycle 25 turns out to be large, then we can expect fireworks at any time, but the last few cycles have seen their strongest storms at the end – near the solar equator. This is part of the history of the delta!
Then there is another factor – when they happen, if they seriously affect us. The Sun has a “hit zone” where the eruption can be what we call “geoeffective”, and this is on the eastern side of the solar disk, because events take a certain amount of time to spiral out of the Sun and hit us. So there is a caveat, and we’ve probably dodged bullets many times in the past – the 2012 event could be an example of this!
In fact, the entire area of space weather – things like solar wind, solar flares, coronal mass ejections, and so on – is in some sense in its infancy. We still have a long way to go to predict these things. We are currently getting some kind of snapshot of what is happening in the solar system.
Deputy Director for Science, NASA Heliophysics Division
Several scientists have conducted statistical studies on the likelihood of an event like Carrington. In 2012, Peter Riley calculated that over the next decade, the chances of an event like Carrington would be between 10% and 12%. However, later studies using more sophisticated statistics yielded slightly lower numbers – closer to 2%. In a 2012 study, a hypothetical superstorm was modeled as an independent event, but the peculiarity of events such as solar flares and earthquakes is that they are in fact deeply related to the events that precede and follow them. We may be able to better predict these things in the future, but it will take some time.
Having said that, we’ve come a long way. We have very sophisticated physics-based computer models that can give us some insight into space weather phenomena that could affect the Earth or elsewhere in the solar system that we care about. These would be events such as coronal mass ejections, when an eruption on the Sun throws billions of tons of plasma into space.
Most of this activity comes from magnetic regions on the Sun, most notably sunspots. If you want to predict what’s going on, you first need to go back and look at the sunspots. To predict whether a sunspot will actually cause a solar flare, we look at its size and shape, and then we look at past data for similar types of sunspots and say: Well, in the past we have seen that 9 out of 10 times such a sunspot could cause a solar flare a certain size. We then use that as a probability.
Of course, this is just counting – it is not really science because the physics of what is happening is really complex, but we are starting to combine a newer and better understanding of physics with computer models, and perhaps the day will come when we have a more complex computer model. which can tell us when a solar flare will occur. And since, generally, the larger the solar flare, the more likely it is to lead to one of these solar eruptions, then you can better understand when a solar superstorm will occur.
This would be important information, as such super storms could interfere with our ability to communicate with satellites or with each other here on Earth. In some extreme cases, they can actually affect our power grid. Given the technical infrastructure we have, something like the Carrington event of 1859 could have had a much greater impact.
The good news is that we will have time – a large drop of matter released by a solar superstorm takes 1-3 days to reach Earth, so once it is identified, you will have time to prepare. NOAA will send an alert to relevant industries such as airlines and energy companies and inform them that something is approaching us, and then they will change their flight plans and cut or disconnect certain electrical circuits.
Senior Lecturer in Applied Mathematics at the University of Sydney, studying computational mathematics, fluid mechanics and solar physics.
The short answer is “nobody knows for sure.” To be precise, solar storms are very similar to any other extreme event. This is almost the same as asking, “When is the next earthquake going to happen?” “When will the next big hurricane hit a city of over 5 million?” or “When will the next pandemic happen?” In some cases, during extreme events, you can have an idea when they might happen as we approach the event… For example, hurricanes move slowly enough to be tracked.
Solar storms are somewhat similar to all this. We already know that it takes them several days to get to Earth. But we are not aware of their extended signatures, if any.
The last time a truly large-scale event happened on Earth was in 1859. We don’t know if this event was 1 in 1000 years old or 1 in 100 years old, and it’s time for us to do another one. Another feature of solar activity is that it, like hurricanes, passes through the “seasons”, although the full cycle lasts 11 years. If you think of a stormy season as summer, then now we have spring. The sun should be much more active in about 5 years. This is the next time a big solar storm can happen. But, of course, we could get away unscathed, and then the next storm will be in about 15 years, and so on.
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