Could a Solar Storm Hit Earth?

With the weather on Earth getting more extreme by the day, you might think you have enough to worry about. But did you know there are storms in space, too?

A solar storm is an eruption of mass and energy that occurs at the surface of the sun. These solar storms can go on for as little as a few minutes or as long as several hours. They can even impact Earth in a significant way, but that begs the question: Could a solar storm hit Earth? Let's take a look at space weather and how it can affect us.

With our naked eyes, the sun can appear static, placid and constant. But in reality, our sun is an enormous thermonuclear reactor, which fuses hydrogen atoms into helium and produces million-degree temperatures and intense magnetic fields. The outer layer of the sun is like a pot of boiling water, with bubbles of hot, electrified gas — electrons and protons in a fourth state of matter known as plasma — that circulate up from the interior and burst out into space.

Scientists believe that high-energy charged particles are released from the sun by solar flares that pour out from the surface of the sun and by shocks that form at the front of coronal mass ejections (CMEs). This means our sun bathes the earth as well as the rest of our solar system with electrically charged particles and magnetic fields. These solar bursts are a form of space weather.

A solar burst of magnetic energy can include solar flares, high-speed solar winds, solar energetic particles and CMEs. A large CME can contain a billion tons of matter that can be accelerated to several million miles per hour in a spectacular explosion. Solar material streams out through the interplanetary medium, impacting any planet or spacecraft in its path. A CME cloud can also erupt from the sun in any direction, but a CME will only impact Earth when it occurs on the side of the sun that faces us. In other words, for a solar storm to hit Earth and cause an impact, the CME cloud would need to be aimed at us.

When a CME cloud plows through the solar wind, high-velocity solar energetic particles can be produced, and because they are charged, they must follow the magnetic field lines that pervade the space between the sun and the earth. Therefore, only the charged particles that follow magnetic field lines that intersect with Earth will result in impacts.

When the charged particles from a solar storm follow the magnetic field lines all the way to Earth, they collide with Earth's magnetic field and trapped radiation belts, which can cause an aurora. An aurora forms when magnetic particles in the solar wind interact with Earth's magnetosphere.

These same particles can also produce their own magnetic fields, which can modify our magnetic field. The amount of the sun's geomagnetic activity varies over 11-year cycles, which means there are times when solar activity and solar storms are more frequent. We know this because people have been observing auroras and drawing pictures of them for thousands of years.

But are auroras dangerous? Modern society depends on technologies that are indeed susceptible to the extremes of space weather. Strong electrical currents driven along Earth's surface during aurora events can affect compass readings and contribute to the corrosion of oil and gas pipelines. A particularly strong solar storm could have serious effects, such as electrical surges that knock out the power grid, which can lead to brownouts and blackouts, or disrupt cell phone service.

Changes in the ionosphere during geomagnetic storms can also interfere with high-frequency radio communications and Global Positioning System navigation. The effect of these geomagnetic storms can linger in Earth's magnetosphere and atmosphere for days or even weeks.

As society's reliance on technological systems grows, so does our vulnerability to solar storms. The ultimate goal in studying space weather is to gain the ability to foretell events and conditions on the sun that could produce harmful societal and economic effects with sufficient accuracy and far enough in advance to allow preventive or mitigating actions to be taken.

So, could a solar storm hit Earth? In short, yes — these storms can affect us, but it's not quite as intense as you might imagine.

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