Earth is bracing for a 'severe' geomagnetic storm and it probably won't be the last for this year

• NOAA has forecasted a "severe" geomagnetic storm to hit Earth this Friday, triggering aurora borealis.
• This storm comes as we approach solar maximum: the peak of solar activity during the sun's 11-year cycle.

A cluster of giant sunspots called region 3664 has been shooting out powerful eruptions, called coronal mass ejections, over the last several days.

Right now, at least five of them are on a direct collision course with Earth, shooting through space at 560 miles per second. As a result, the National Oceanic and Atmospheric Administration issued a rare forecast for a "severe" G4 geomagnetic storm to hit Earth this Friday.

It's the first G4 forecast NOAA has issued since 2005. But severe geomagnetic storms like this could become more common in the coming months as we approach what's called solar maximum: the peak of solar activity during the sun's 11-year cycle.

"That means that there'll be a lot more sunspots, and the sunspots will be much larger," Alex Young, the associate director for science at NASA Goddard's Heliophysics Science Division, told Business Insider.

What is solar maximum?

Roughly every 11 years or so, the sun's magnetic field flips: its north and south poles swap places.

Over the course of this 11-year cycle, the sun's activity — which is governed by its magnetic field — fluctuates.

The last time the sun's poles flipped and the sun reached solar maximum was in 2013.

That means we're due for the next round of heightened solar activity. "We are just now reaching the peak," Young said.

During solar maximum, the sun develops more and larger sunspots, like the ones in region 3664, compared to quieter periods of solar activity.

"They come in little spurts," Young said. "And those spurts of sunspots will get closer and closer together, and the sunspots that appear will be typically larger, more complicated, and will produce more solar activity," which can generate severe geomagnetic storms.

What does this mean for Earth?

More and larger sunspots mean the sun is more prone to release powerful eruptions called coronal mass ejections, like the ones headed for Earth right now.

Severe geomagnetic storms like the one forecasted to hit this Friday are rare. But entering solar maximum means we could see more of them this year.

The good news is that we'll likely have more chances to see dazzling auroras in the Northern Hemisphere this year. The bad news is that these storms could mess with satellites and the power grid.

We could experience more power outages, communication blackouts, and GPS disruptions.

In the event that a geomagnetic storm does trigger a power outage where you live, make sure to keep your refrigerator closed, unplug your appliances, and contact local officials about heating and cooling locations. To prepare for a GPS outage, make sure you have printed or written copies of directions to important locations like hospitals.