The sun is about to get more active than it has for a decade — and it could lead to power outages, grounded flights, and stunning auroras

• The sun is entering a period of peak activity that will last several years, an expert said.
• This means the sun will produce more solar flares, which are powerful bursts of energy.
• Solar flares can disrupt radio communications and electric power grids on Earth.

The sun may be waking up after almost a decade of relative calm, say scientists — and that could cause problems on Earth.

The solar storms that rage on our star during its active period create bursts of electromagnetic energy, which can affect everything from the power grid to GPS signals.

These so-called solar maximums occur roughly every 11 years, and haven't been much of a problem in the past.

Scientists, however, fear that our reliance on electricity and interconnectivity could mean we're far more vulnerable to their affects this time around.

The sun's poles are flipping

The sun is a big ball of plasma, heated at its center. The plasma, which is made of charged particles, boils towards the surface, cools down and sinks back towards the core again.

That motion, called convection, is what creates strong magnetic fields at the poles and smaller, local magnetic fields at the surface of the sun.

Every 11 years or so, the sun becomes "convectively unstable," meaning the magnetic fields on the sun become so unstable that the magnetic north and south poles abruptly flip, throwing our star's polarity out of whack, said Mathew Owens, a professor of space physics at the University of Reading.

That instability causes havoc in the magnetic fields at the surface of the sun, which become much more active. That's when the so-called solar maximum happens.

Solar storms could ground planes

The sun is much more likely to throw energy our way during its maxima.

As the sun's local magnetic fields get more tangled and crash into each other, they can explode. Energy and charged particles from the sun are then ejected into space.

That energy can affect communication by messing with the ionosphere, a layer of charged particles in our upper atmosphere. That could cause problems for air travel.

"Space weather can ground flights," said Owens. "The FAA won't allow flights if they don't have both radio and satellite communications."

A 2023 study looking at flight records over 22 years found that planes are 21% more likely to be delayed by at least 30 minutes when the sun is very active.

The rays can change the magnetic fields in the ionosphere, which can affect GPS signals that have to pierce through that layer to reach Earth.

Radio signals sent from Earth also need to bounce off of the ionosphere to get from one point to the other, which is less efficient in rough space weather.

Granted, radio signals are much less important to basic communications today. But several industries use radio signals to back up their other communications systems in case of failure.

There may be power outages

As the geomagnetic storm messes with the ionosphere's magnetic charge, it creates currents in the ionosphere. Those currents in our upper atmosphere interact with the particles in the ground. The interaction between these particles creates strong electrical currents that can flood infrastructure on earth.

This can trigger some bizarre phenomena. In one example is in 1972, US military pilots flying south of Haiphong harbor in North Vietnam saw two dozen sea mines explode in the water, without any apparent cause.

A 2018 study looking at space weather at the time later concluded that this was caused by a huge solar storm.

If the currents flood the electrical grid, they can blow up transformers.

One damaged transformer won't cause much of an issue. But if a huge geomagnetic storm heads towards Earth — a storm so big it would "probably give us aurora down to the equators" — that could cause several transformers to go at once.

It could also overwhelm other transformers that could then blow up, knocking out the whole grid, said Owens.

In that case, restarting the grid "could be a matter of weeks or even months. Then you lose refrigeration, you lose power to hospitals, things get quite serious quite rapidly," said Owens.

So far, we've been lucky. The worst solar storm we've seen happened in 1859. But we didn't rely as much on electricity back then as we do now, so the only thing that was knocked out was telegraph lines.

Still, a space weather event in 1989 shows just how vulnerable we've become. A huge geomagnetic storm that hit Montreal, Quebec, on March 13 of that year cut power for six million people for nine hours.

Auroras may become bigger and brighter

As these geomagnetic storms crash into the ionosphere, they can make auroras shine big and bright.

"The aurora oval that sits up over the northern and southern poles is a result of currents flowing in the Earth's atmosphere. And they're nearly always there, but they become very much stronger when we've got a geomagnetic storm going on," said Owens.

We're starting to see some of the effects of these solar flares. Auroras were seen as far down as the southern UK on Sunday night, and more are expected in the coming days, the BBC reported.

The sun itself might be erupting in more beautiful formations. This has already started happening. NASA spotted a rare polar vortex earlier this month.

Astronauts will become more vulnerable to lethal space radiation

The sun also lets off radioactive material called solar energetic particles, which can be dangerous to astronauts.

Humans on Earth are shielded from that radiation, as most of it bounces off of the ionosphere and the rest is absorbed by the atmosphere. Even the International Space Station is still under the protection of the ionosphere.

But if the radiation hits an astronaut in outer space, it can be very dangerous, said Owens.

"If you are trying to send a crew to the moon or Mars, you really need to worry about these things because that is a serious, potentially fatal radiation dose," said Owens.

So far, astronauts have been lucky. In August 1972, two Apollo crewed missions narrowly escaped a huge solar storm. Apollo 16 landed back in April, while Apollo 17 launched in December.

"They missed it purely by chance and it could have been fatal for the astronauts at the time," said Owens.

But as SpaceX and NASA aim to ramp up missions in coming years, they will need to prepare for solar storms. The issue is that to date, there's no good way to shield astronauts in space, said Owens.

We're likely not prepared for rough space weather

Owens said that if the 1859 solar storm were to happen today we'd be "far more susceptible."

The issue is that with each decade we become more dependent on electrical infrastructure, he said. And the last solar cycle, which peaked around 2010, was particularly quiet and may have lulled us into a false sense of security.

"It was the smallest we'd had for about a hundred years," said Owens, adding: "The danger of going from a small cycle to a slightly bigger one is that you then realize where all the vulnerabilities are."

Still, we're not in immediate danger. Physicists predict that this cycle will not be the biggest we've ever seen, and we're getting better at spotting storms to be able to prepare for them before they come.

Scientists are also learning more and more about our sun. NASA's Parker Solar Probe, for instance, is heading for the sun right now and will provide us with unprecedented images and exciting new data about the sun in December.