Extreme solar storms can strike out of the blue. Are we really ready?

An unexpected solar storm in 2003 disrupted hundreds of flights around the world, caused spacecraft controllers to lose contact with satellites in low Earth orbit for several days and cut off electricity for tens of thousands of people in Sweden. Now, almost 20 years later, one of the world’s leading weather forecasters admits that our life-giving star can still take us by surprise.

October 2003 was a quiet month at the Space Weather Prediction Center (SWPC) of the US National Atmospheric and Oceanic Administration (NOAA). The sleepy sun was nearing its minimum in its 11-year activity cycle, producing a mediocre 100 sunspots per month. Everything changed in a week. The Sun flared up with the largest sunspot accumulation in more than 10 years and unleashed a flurry of flares and plasma eruptions on Earth that caused the most violent space weather event in recent history.

“I remember that week in October very clearly,” Bill Murtagh, NOAA SWPC program coordinator, who was the space weather forecaster on duty at the time, told “Partly because it was my birthday, but mostly because the sun was unremarkable. We had no idea what would happen in just a week.”

On the subject: Wrath of the sun: the most powerful solar storms in history

The event, which has since entered the history books as Halloween solar storms, wasn’t even the scariest thing the sun could do. In fact, the storms of 2003 released only about a tenth of the energy of the two most powerful solar storms in human history – the so-called Carrington event of 1859 and the New York railroad storm of 1921, both of which disrupted the telegraph service at that time. . around the world.

After those storms, everything changed. The telegraph is now a thing of the past, but many of the new technologies we increasingly rely on are equally vulnerable to space weather flares. The problem, Murtagh says, is that space weather forecasters are only marginally better at predicting these storms than they were in 2003.

“In fact, we have identified space weather in some of our national security documents as one of several threats that could have nationwide or even global implications,” Murtagh said. “It’s like a pandemic. And we saw what happened with the pandemic.”

Not seeing this

What happened to the sun that fateful week in 2003 when it went berserk with such a minor warning? It rotated on its axis as it has done for millennia, revealing a cluster of sunspots 13 times the size of the Earth that must have simmered out of view for quite some time.

Sunspots are cooler regions on the surface of the Sun where the star’s magnetic field is distorted so severely that the magnetic lines eventually explode, releasing radiation in the form of solar flares and plasma in the form of coronal mass ejections (CMEs).

As soon as this sunspot was directed towards Earth in October 2003, a flurry of 17 solar flares and coronal mass ejections followed, causing massive radio blackouts and geomagnetic storms in the Earth’s atmosphere.

Related: NASA solar forecast turns out to be wrong. This team’s model is still on the move.

The sun released an X-class flare on May 10, 2022.

Solar flares reach Earth within minutes and disrupt radio transmission in the atmosphere. (Image credit: NASA/SDO/

During this week, 59% of NASA’s space missions “experienced effects” according to a NOAA report. (will open in a new tab). Japan’s Advanced Earth Observation Satellite 2 lost contact with ground control during a storm and never recovered. The US Space Surveillance Network, which monitors objects in space, completely lost sight of all satellites and space debris in low Earth orbit for several days. In some parts of the planet, there was a radio and GPS outage, which led to financial losses for airline companies that had to reroute hundreds of flights. In the Swedish city of Malmö, high-voltage power lines failed; the ensuing hour-long blackout lured people into the elevators and stopped trains in their tracks.

“During that two-week period, we had what I often refer to as the Great Awakening,” said Murtagh, who later led a team that produced an extensive NOAA report investigating the aftermath of the incident. “There were so many different sectors that were suddenly affected and interested in our warnings.”

Do we know better?

Fast forward almost 20 years. The sun continues to rotate on its axis, and weather forecasters still have very little information about what is happening on the side facing away from the Earth.

By observing visible sunspots, they get a rough idea of ​​the likelihood of a solar flare or coronal mass ejection. However, they have no way of knowing the exact time and strength of the impending flare, and they have only a limited ability to predict its impact on Earth.

The mayhem of Halloween storms was caused by both solar flares and the CME. Both of these phenomena occur in sunspots when the twisted magnetic fields in these regions break apart and reconnect. The two often go hand in hand, but arrive on Earth on different timescales.

“A solar flare is electromagnetic radiation, meaning light, including visible and all other wavelengths, including gamma rays and radio frequencies,” Juha Pekka Luntama, head of space weather at the European Space Agency (ESA), told “The moment we see it, it’s already affecting the Earth’s ionosphere and causing disturbances.”

The radiation of solar flares “ionizes the upper atmosphere at altitudes of more than 80 kilometers.” [50 miles]”, – said Luntama. – It excites the atoms and molecules there, and this can affect the propagation of the signal from [GPS and GNSS] satellites. If you have a GPS or GNSS receiver, then you will see a navigation error because the characteristics of the upper atmosphere are changing.”

coronal mass ejection close-up

It takes up to three days for a coronal mass ejection to reach a planet, but its effects usually last longer. (Image credit: NASA/Goddard Space Flight Center)

Solar flares come in different strengths, the most powerful being classified as X-flares. The strength of the flash is further defined by a number, where each successive digit is a multiple of the base strength. During the Halloween storms, the Sun produced a record X28 flare, the most powerful ever observed, which, according to NASA (will open in a new tab), temporarily overloaded satellite sensors. The outbreak, Luntama said, knocked out GPS systems in North America for several hours. According to NOAA, the positioning error of GPS-based navigation systems used in aviation was so great that the system was completely unusable.

While the impact of a solar flare immediately affects the dayside of the globe, CMEs that often originate from the Sun during the same break in magnetic field lines give space weather forecasters some time to prepare.

“The effects of a solar flare last for several hours at worst,” Luntama said. “Conditions return to normal, and then the CME arrives and the geomagnetic storm begins. So there is a first collision, then a small gap. And then another collision. And they all come from the same solar event. .”

CME takes up to three days to reach Earth. In some cases, the orientation of their magnetic field is such that they are repelled by the Earth’s magnetic shield and no geomagnetic storm occurs.

The NOAA Deep Space Climate Observatory, or DSCOVR, located about 1 million miles (1.5 million kilometers) from Earth towards the Sun, provides early warning of the strength of an incoming geomagnetic storm about an hour before the CME hits Earth. The Halloween storms, however, produced one CME so strong that its impacts were evident almost as soon as it broke out of the sun.

“This particular event that happened on October 28th was so impressive that we knew how big the impact would be long before it reached [DSCOVR]Murtagh said. — In fact, we predicted the most powerful geomagnetic storm. [directly] from an eruption in the sun. It may have been the only time we’ve ever done this.”

The NOAA DSCOVR satellite measures the strength of a coronal mass ejection about an hour before it hits Earth.

The NOAA DSCOVR satellite measures the strength of a coronal mass ejection about an hour before it hits Earth. (Image credit: NOAA)


Despite decades of research, scientists still know very little about the Sun’s activity and the complexities of the space weather it creates. While major solar storms are on the list of hazards that could have nationwide impacts in many countries, progress in mitigating potential impacts is not as fast as it might need to be, Murtagh admits. However, he says awareness has improved and there are rules in place to keep disruptions to a minimum.

“There is no doubt that we are now better than we were in many areas,” Murtagh said. “For example, in the energy sector, the US government has required transmission companies to assess the vulnerability of their equipment to these geomagnetic storms and do something about it. On the other hand, there are now new problems, for example, with new satellite mega-constellations.”

An incident in February 2022 demonstrated the severity of the problems space weather can cause for satellite operators when SpaceX lost a batch of brand new Starlink satellites after launching them into a moderate geomagnetic storm. Disturbances in the upper atmosphere caused the satellites to lose altitude and die. Other operators have also reported problems maintaining the altitude of their low orbiting satellites.

The European Space Agency plans to launch a new solar observation mission to predict space weather.

The European Space Agency plans to launch a new solar observation mission to predict space weather. (Image credit: ESA)

Murtagh acknowledges that a storm the size of a Carrington event or even a Halloween storm will wreak havoc on satellites, and it could still happen with as little warning as the CME and solar flares in October 2003. In the future, space weather forecasting will get a little easier as a new mission called Vigil (will open in a new tab)will be launched by the European Space Agency in 2025, which will finally allow forecasters to look “around the corner” at what is happening on the as-yet-unseen side of the Sun.

“This mission will be a huge event and will help us a lot not to be taken by surprise, as we were in 2003,” Murtagh said. “It will also help us get a side view of the CME leaving the Sun and approaching the Earth. This will help us improve tracking,” and with it future space weather forecasts.

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook.

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